* Strike on Gaza police chief's home kills 18 - Gaza health ministry
* Hamas fires biggest rocket salvo at Tel Aviv since offensive began
* Israel says ground invasion into Gaza possible
* Israeli fire has killed 145 Palestinians, many of them civilians (Releads with 18 killed in single strike, Tel Aviv rocket salvo, adds Israeli defence minister)
By Nidal al-Mughrabi and Maayan Lubell
GAZA/JERUSALEM, July 12 (Reuters) - An Israeli air strike on the home of Gaza's police chief killed 18 people on Saturday, Gaza's health ministry said, and Hamas fired the largest salvo of rockets yet on Tel Aviv since the start of the Jewish state's offensive in the Palestinian enclave.
The strike on the home of Tayseer Al-Batsh in Gaza City was the deadliest bombing since Israel launched its offensive on Tuesday to end Palestinian rocket fire into its territory.
A source in the Islamist group Hamas, which has fired hundreds of rockets into Israel since Tuesday, said Al-Batsh, was in critical condition. All of those killed in the air strike were members of Al-Batsh's family.
Ashraf Al-Qidra, spokesman for the Gaza Health ministry, said 45 people were wounded and others were still trapped under the rubble where rescue workers were searching.
Hamas earlier claimed responsibility for 10 rockets that were launched at Tel Aviv on Saturday but which caused no casualties or damage.
Sirens sounded across central Israel as people rushed for cover from the rockets. One group of youths sitting at the beach cheered as they saw a rocket intercepted in the night sky. In Gaza, Palestinians stood at rooftops chanting Allah Akbar (God is great), cries that also echoed over mosque loudspeakers.
The Israeli military said three of the rockets fired were intercepted over Tel Aviv and another struck an open area.
Hamas had broadcast a televised statement an hour before the salvo to say it was preparing a major attack on Tel Aviv. The Israeli military said it bombed the rocket launcher used for the salvo.
Israel's offensive has killed 145 Palestinians since Tuesday. Gaza medical officials said at least 82 civilians, including 25 children, were among the dead from the air strikes on the territory into which nearly 2 million people are packed.
A nephew of Ismail Haniyeh, the Hamas political leader in the territory was among six people killed in an air strike in a Gaza street.
A mosque in the central Gaza Strip was bombed to rubble, residents said. The Israeli military said it had housed a weapons cache. Eight other mosques have been damaged by bombing and 537 Gaza houses have either been destroyed or damaged, the Gaza-based Al-Mezan Association for Human Rights said.
Israel is keeping its options open for a possible ground offensive into densely populated Gaza despite international pressure to negotiate a ceasefire in the conflict.
Israeli Defence Minister Moshe Yaalon said he had told troops they might enter the Gaza Strip in the coming days.
"We are attacking and destroying weapon storages, militants' homes, armaments, launchers, rockets ... the damage is great and it grows as time goes by, but it may not be enough, we may need a substantial ground operation," Yaalon said on Facebook.
Some 20,000 reservists have been mobilised for a possible thrust into Gaza.
The U.N. Security Council, after days of discussion, issued a statement calling for a ceasefire and expressed serious concern about the welfare of civilians on both sides.
"The Security Council members called for de-escalation of the situation, restoration of calm and reinstitution of the November 2012 ceasefire," the 15-member body said.
Gaza militants fired more than 100 rockets at Israel on Saturday, the Israeli military said, one of which struck the occupied West Bank Palestinian city of Hebron.
No Israeli has been killed by the rocket salvos due in part to Iron Dome, a partly U.S.-funded interceptor system.
But racing for shelter has become a daily routine for hundreds of thousands of Israelis, and Israel rushed an eighth Iron Dome into service on Saturday to counter stronger-than-expected rocket fire from Gaza.
"In the past week, we carried out a very complex technological exercise to deliver the eighth (Iron Dome) system," a Defence Ministry official said on Israel Radio.
Gaza rocket fire intensified last month after Israel arrested hundreds of Hamas supporters in the occupied West Bank after the abduction there of three Jewish teenagers who were later found killed. A Palestinian youth was then killed in Jerusalem in a suspected revenge attack by Israelis.
'MAP OF PAIN'
Egypt's state news agency said that Egyptian President Abdel Fattah al-Sisi had met with Tony Blair, envoy for the so-called Quartet of United Nations, European Union, Russia and United States, in efforts to secure a truce.
An Israeli government official said Blair had met with Israeli Prime Minister Benjamin Netanyahu on Friday. "There are no serious contacts toward a truce. There are many proposals, but as long as Hamas keeps firing, Israel will keep fighting and will not discuss a truce," the official said.
Cairo played a crucial role in mediating a truce that ended an eight-day war between Hamas and Israel in 2012, when Egypt was governed by Hamas's Muslim Brotherhood allies.
Egypt's current military-backed government is locked in a feud with Hamas over the group's alleged support for jihadi militants in Egypt's Sinai desert - Hamas denies supporting the militants. That could complicate Cairo's efforts at mediation.
Hamas spokesman Sami Abu Zuhri said: "We will not beg for calm and we continue to defend our people. Once we are offered a genuine, coherent and serious proposal, we will look into it."
Israel says Hamas puts innocent Gazans in harm's way by placing weaponry and gunmen in residential areas. A senior Israeli military officer said aircraft had aborted "hundreds" of strikes to avoid collateral damage and that targets bombed were meant to impact Hamas fire capacity.
"We are dealing with a variety of families of targets. If there is a kind of a map, or a map of pain that the enemy sees, we create a lot of pain so that he will have to think first to stop the conflict," the officer said in a briefing to reporters.
Israel says it has hit more than 1,000 targets in Gaza since the start of its offensive.
Casualties on both sides would probably rise sharply if Israeli forces stormed the largely urbanised enclave. A ground invasion of Gaza would be the first since a three-week war with Hamas in 2008-09 in which 1,400 Palestinians and 13 Israelis were killed.
(Additional reporting by Dan Williams in Tel Aviv and Ali Abdelatti and Stephen Kalin in Cairo; Editing by Mark Heinrich, Lynne O'Donnell and Paul Simao)