* Chinese relatives clash with Beijing police, slam Malaysia
* Malaysia PM says MH370 crashed in southern Indian Ocean
* Bad weather forces suspension of search - AMSA
* No hope of survivors; relatives distraught
* China demands Kuala Lumpur share all evidence (Adds comments from U.S. State Department spokeswoman, paragraphs 9-10)
By Megha Rajagopalan and Al-Zaquan Amer Hamzah
BEIJING/KUALA LUMPUR, March 25 (Reuters) - Dozens of distraught relatives of passengers on a lost Malaysian jetliner clashed with police in Beijing on Tuesday, accusing Malaysia of "delays and deception" a day after it confirmed the plane crashed in remote seas off Australia.
About 20 to 30 protesters threw water bottles at the Malaysian embassy and tried to storm the building, demanding to meet the ambassador, witnesses said. Earlier, the relatives, many with tear-stained faces, had linked arms and chanted "Malaysian government has cheated us" and "Malaysia, return our relatives" as they marched peacefully and held banners.
The relatives' grief and anger was unleashed on Monday night after Malaysian Prime Minister Najib Razak announced that Malaysia Airlines Flight MH370, which vanished more than two weeks ago while flying to Beijing from Kuala Lumpur, had crashed in the southern Indian Ocean.
Citing satellite-data analysis by British company Inmarsat , he said there was now no doubt that the Boeing jet came down in the ocean in one of the most remote places on Earth - an implicit admission that all 239 people on board had died.
Bad weather in the region far off Australia's western coast on Tuesday forced the suspension of the search for any wreckage, just as a series of satellite images and other sightings of floating objects had raised hopes that debris from the plane would be found.
Malaysia's confused initial response to the Boeing 777's disappearance and a perception of poor communications has enraged many relatives of the more than 150 Chinese passengers and has strained ties between Beijing and Kuala Lumpur.
Following Najib's announcement, Chinese Deputy Foreign Minister Xie Hangsheng demanded that Malaysia hand over all relevant satellite analysis showing how Malaysia had reached its conclusion about the jet's fate.
In a separate statement, Chinese Premier Li Keqiang said China would ask Malaysia to provide more detailed and accurate information on the plane, according to a government microblog account. Chinese President Xi Jinping will send a special envoy to Kuala Lumpur to consult with the Malaysian government, state news agency Xinhua said on Tuesday.
The U.S. State Department said the United States was cooperating with Malaysia and working to verify the data from Inmarsat and the Kuala Lumpur government about the course of the U.S.-made plane.
"Basically, we are going back and looking at how they got to where they got to and seeing if our math experts and folks can get to the same place as well," State Department spokeswoman Marie Harf told a regular news briefing.
A group reportedly representing families issued a statement describing the Malaysian airline, government and military as "executioners" who constantly tried to delay and deceive them.
"We will take every possible means to pursue the unforgivable crimes and responsibility of all three," said the statement on the microblog of the Malaysia Airlines MH370 Family Committee.
The relatives protesting in Beijing held signs that said: "MH370, Don't let us wait too long!" and "1.3 billion people are waiting to greet the plane." They wore matching T-shirts that said: "Best of luck to MH370, return home safely."
"We've waited for 18 days and still, you make us wait. How long are we supposed to hang on?" a woman surnamed Zhang told Reuters.
The protest ended after a few hours when police told demonstrators to get on buses and escorted them away.
Criticism of the Malaysian national carrier mounted after some relatives of those on board first received the news that the search for survivors was over in an SMS, or text message, from the airline saying, "We have to assume beyond all reasonable doubt that MH370 has been lost and none of those on board survived."
At a news conference at Kuala Lumpur's international airport on Tuesday, company officials defended the move, saying the text message had only been sent as a "last resort" to ensure that some relatives did not hear the news first from media outlets.
"This is a time of extraordinary emotions, and we fully understand," said Malaysia Airlines Chairman Mohd Nur Yusof. "In fact, we really feel for the next of kin. In terms of how they react, it's emotional."
Asked whether he would resign over the crisis, the airline's chief executive, Ahmad Jauhari Yahya, said that would be a personal decision to be made later.
WRECKAGE COULD HOLD KEY
Flight MH370 vanished from civilian radar screens less than an hour after taking off on March 8. No confirmed debris from the plane has been found since.
Investigators believe someone on the flight may have shut off the plane's communications systems. Partial military radar tracking showed it turning west and recrossing the Malay Peninsula, apparently under the control of a skilled pilot.
Recovery of wreckage could unlock clues about why the plane had diverted so far off course. Theories range from a hijacking to sabotage or a possible suicide by one of the pilots, but investigators have not ruled out technical problems.
As a result of the new satellite analysis, the international search effort has been narrowed to focus solely on the southern end of the possible route - a still-massive area of 469,000 square miles (1.2 million sq km) - Malaysian acting Transport Minister Hishammuddin Hussein told reporters.
The search site is far from commercial flight paths about 2,500 km (1,550 miles) southwest of Perth, a region of deep, frigid seas known as the Roaring 40s where storm-force winds and huge waves are commonplace.
Malaysia Airlines said in a statement that it would make arrangements to fly relatives to Australia once it had approval from the investigating authorities.
Australia's Immigration Minister Scott Morrison said his department was working with the airline and Beijing to facilitate visas. Relatives would be given tourist visas with the usual fees waived, he said.
COSTLY, DIFFICULT INVESTIGATION
Najib's announcement opened the way for what will be one of the most costly, difficult air crash investigations ever. Normally, an official investigation can only begin once a crash site has been identified. That would give Malaysia power to coordinate and sift evidence.
A government source told Reuters that Malaysia would lead the investigation, but hoped other countries, especially Australia, would play a major role.
The United States said it was sending an undersea Navy drone to Australia, in addition to a high-tech black box detector, to help in the search.
But the black box detector would not arrive in the search area until April 5, Hishammuddin said, leaving only a few days to pick up locator beacons from the box that stop about a month after a crash due to limited battery life.
The so-called black boxes - the cockpit voice recorder and flight data recorder - record what happens during flight.
Najib said Inmarsat had performed further calculations on data gleaned from faint pings picked up by satellite that initially only narrowed the search area to two massive arcs.
Giving more details on the analysis on Tuesday, Hishammuddin said it showed that at some time after 0011 GMT - about six hours after its last sighting by Malaysian military radar on March 8 - the aircraft was no longer able to communicate with the ground station.
"This is consistent with the maximum endurance of the aircraft," he said.
He said there was evidence of a further "partial handshake" between the satellite and the aircraft eight minutes later, but that this transmission was not understood and was being analyzed. (Additional reporting by Ben Blanchard, Megha Rajagopalan and Joseph Campbell in Beijing, Stuart Grudgings, Michael Martina, Siva Govindasamy and A. Ananthalakshmi in Kuala Lumpur; Phil Stewart and David Brunnstrom in Washington; Jane Wardell in Sydney and Matt Siegel in Perth; Writing by Stuart Grudgings; Editing by Alex Richardson and Jonathan Oatis)