* At least 150 Taliban involved in attack
* Fighting comes day after key U.S-Pakistan meeting
(For full coverage of Pakistan and Afghanistan, click on [nAFPAK])
(Adds 10 militants killed in air strikes)
By Hassan Mehmood
HANGU, Pakistan, March 26 (Reuters) - Pakistani troops killed at least 34 militants after about 150 Taliban attacked a military checkpost in the northwest on Friday, challenging government assertions crackdowns have weakened the group.
Homegrown Taliban rebels are seeking to topple the U.S.-backed government of unpopular President Asif Ali Zardari, who has been pressured to hand over some of his key powers, such as dissolving parliament and appointing military chiefs.
A senior military officer and four paramilitary soldiers were also killed in the attack in Orakzai, a day after Pakistani jets killed nearly 50 people, mostly militants, in strikes on a school and a seminary in the same region, a government official said.
Fourteen soldiers were wounded in the Taliban assault.
Orakzai, one of seven Pakistani tribal regions near the Afghan border, also known as agencies, has seen a surge in military attacks in recent months, targeting militants who were driven out of their bastion of South Waziristan.
Pakistan mounted two offensives last year in the northwestern Swat Valley and in South Waziristan on the Afghan border, which it says threw al Qaeda-linked militants into disarray.
But despite losing ground, the Taliban hit back with bombings that killed hundreds, prompting troops to step up attacks in other northwestern regions where militants are believed to have taken refuge after offensives.
In the latest attack, about 150 Taliban launched a pre-dawn assault on a checkpoint in Orakzai, triggering fierce fighting.
"They attacked from three sides which continued for nearly three hours in which a lieutenant colonel and four other security officials were killed," said government official Khaista Rehman.
"Security forces launched the counter-attack in which 24 militants have been killed," he said. A paramilitary official, said as many as 30 militants may have been killed.
Army jets and helicopter gunships later targeted suspected militant hideouts in various parts of Orakzai and killed another 10 militants, said government official Mohammad Asghar Khan.
Orakzai is considered a militant stronghold of Pakistan Taliban chief Hakimullah Mehsud, who is widely believed to have been killed in a U.S. drone aircraft attack in January.
Pakistani action against militants along its Afghan border is seen as crucial to the U.S. efforts to bring stability to Afghanistan, particularly as Washington sends more troops there to fight a raging Taliban insurgency before a gradual withdrawal starts in 2011.
The two allies pledged increased cooperation in tackling militants during two days of talks in Washington that ended on Thursday, with Washington promising to speed up overdue military payments.
U.S. Defense Secretary Robert Gates praised Pakistan for increased coordination over stabilizing Afghanistan, including the recent arrest of a key Afghan Taliban commander in what has been described as a joint American-Pakistani raid in Karachi. (Additional reporting by Augustine Anthony; Editing by Michael Georgy)