The US has lost a strong ally with the resignation of President Pervez Musharraf but Pakistan's civilian government is unlikely to make any major change to his security policy, according to analysts.

The former army chief, who had earned the nickname "Busharraf" for his ties with the US President, stepped down on Monday after becoming increasingly unpopular, partly because of his close alliance with the US.

Mr Musharraf single-handedly steered Pakistan's security policy after he signed up to the US-led war on terrorism following the September 11 attacks. He survived at least two al Qaeda-inspired assassination attempts.

But Mr Musharraf was never able to shake off nagging suspicion Pakistan was not doing all it could to tackle militants, in particular to stop Taliban raids into Afghanistan from remote havens in semi-autonomous ethnic Pashtun areas on the border.

Questions have now been raised about the new government and, if it is weak and beset by political feuding, whether it will be able at least to maintain Mr Musharraf's policy, even though the US often called upon him to do more.

"With the resignation of President Pervez Musharraf ... the future of the US-Pakistan partnership against terrorism may now be in doubt," US Congressman Duncan Hunter, senior Republican on the House Armed Services Committee, said in a statement.

"The new Pakistani government may or may not prove to be as reliable an ally ... as President Musharraf has been," he said.

But analysts said while the new government might introduce some cosmetic changes in its policy to win public support for a war many Pakistanis oppose, it was unlikely to bring about any drastic shifts.

"I don't think there would be any significant change in the policy because if the past five months are anything to go by, I haven't seen any change," said Rustam Shah Mohmand, a former Pakistani ambassador to Afghanistan.

"It's the same old policy pursued by Mr Musharraf."

The US will keep up the pressure no matter who wins the US election in November. Both US Presidential candidates, John McCain and Barack Obama, stressed on Monday the need for Pakistan to focus on security now that the question of Mr Musharraf's Presidency had been dealt with.

A former security chief in the Pashtun tribal areas, Mehmood Shah, said the militants were not giving up their violent campaign, leaving the government no choice but to press on with Mr Musharraf's policies.