* Families fleeing affected area for safer cities
* Pakistani official says strikes are "retaliatory"
* Locals fear army preparing for big military offensive (Adds senior Pakistani official speaking in Washington)
By Jibran Ahmed and David Brunnstrom
PESHAWAR, Pakistan/WASHINGTON Feb 25 (Reuters) - The Pakistani military launched new air strikes targeting militant hideouts in the North Waziristan tribal region on Tuesday, killing at least 30 people, and a senior government official warned of a big offensive unless the Taliban showed they were serious about negotiations.
Pakistani fighter jets have been pounding targets in the region since the government's efforts to engage Taliban insurgents in peace negotiations broke down this month.
North Waziristan residents have been fleeing the area on the Afghan border in recent days, anticipating a full-scale military offensive, leaving homes, shops and villages behind and settling in safer areas, such as Bannu, a town on the edge of the region.
"The militants had captured a stretch between South Waziristan and North Waziristan and had established training centres where they were also preparing suicide bombers," said one military official, who spoke on condition of anonymity.
Another security official said at least 30 "terrorists" had been killed in early morning air strikes.
A senior Pakistani government official, speaking in Washington, said the current strikes were "retaliatory" in response to a series of militant attacks, including the killing of 23 Pakistani soldiers in January.
He said the government would prefer a negotiated settlement with the Taliban but added: "If the negotiations ... do not follow the trajectory that has been planned ... there will be operations not only in North Waziristan but wherever necessary."
"It's because while they are negotiating they are killing people," the official, who asked not to be named, told reporters.
He said such an offensive would see the Haqqani militant network driven out of North Waziristan and made clear that such an effort would be coordinated with U.S.-led forces in Afghanistan to prevent militants escaping there.
"There is an ongoing cooperation. Intelligence sharing is ongoing," he said.
"If they (militants) cross over, somebody should be there to receive them and the operation will be well known and hopefully it will be coordinated also," the official said. "Our operation will not be under the table so that people can't see it. It will be a very visible operation."
Asked whether the Pakistani operation could involve ground troops, the official said there were already large numbers in North Waziristan.
"We have troops there; we just have to sort of reposition right, left, where we want to undertake operations."
The official said the Pakistani Taliban had said publicly it was serious about negotiations.
"They are progressing, albeit in a rough patch, but I have a feeling that these negotiations will not prolong beyond a certain level and in case they succeed, lucky for everybody - many lives will be saved - but if they fail, then all other options are on the table."
The latest air strikes took place mainly in the remote Shawal valley and Dattakhel areas of North Waziristan, said to be sites of militant training facilities and compounds.
It was impossible to verify how many civilians might have been killed or wounded because journalists and independent observers are not allowed to operate freely in the area.
It was also hard to estimate how many people were fleeing the region. One tribesman, Naqibullah Khan, told Reuters he was scared for his family because of persistent rumours that the army would soon launch a full-scale offensive.
Fears of a major operation heightened this month after talks broke down and the Islamist Taliban told the government there was no chance of peace unless Islamabad changed its political and legal system and officially embraced Islamic law.
"Every day heavy arms and ammunition are being shifted to Waziristan and then warplanes bomb villages," Khan said by telephone from Bannu. Two-thirds of the population of his village in the Mir Ali area have fled, he said.
"We were hearing that the government would soon launch a big military operation in Waziristan."
Another tribesman, Gul Jabbar, 48, said by telephone that he had left his shop and home behind in a village after it was hit by fighter jets last week.
"The government is doing nothing to help the people leaving their villages or helping them find accommodation in Bannu," he said. (Writing by Maria Golovnina; Editing by Ron Popeski and Mohammad Zargham)