A Taliban suicide car bomb struck Pakistani police on Thursday for a second day, killing 25 people as the militia vowed no reprieve in their quest to avenge the US killing of Osama bin Laden.

The attack defied the government's authorisation of "all means" to wipe out militants, which nonetheless stopped short of unveiling specific new measures despite a string of humiliating Taliban attacks on security forces.

As Pakistan grapples with the fallout from the American special forces raid that killed the Al-Qaeda chief on May 2, US Secretary of State Hillary Clinton on Thursday again backed "long-term" security ties with the troubled ally.

Police deputy inspector general Masood Khan Afridi said, "The bomber blew up the car at a checkpoint close to the police station."

A pick-up vehicle crossed the district police office in the town of Hangu, police official Latif Khan said, before exploding at a barrier outside the city police station, creating a 10-foot long and foot-deep crater.

"The buildings housing the police station, DPO office and nearby residence of the DPO were partially damaged but at least 15 shops, including a tea house and a restaurant, are completely razed," he said.

Sahibzada Mohammad Anis, the top administrative official for Hangu, said that 25 people had died and 36 others were wounded.

Regional police spokesman Fazal Naeem feared most of those killed were policemen and predicted that the toll would rise, because there are offices and residences of senior police and administration officials near the attack site.

Hangu district has a history of violence between minority Shiite and majority Sunni sects, and is close to tribal areas bordering Afghanistan where Taliban and Al-Qaeda-linked militants have carved out strongholds.

"We accept responsibility for this attack. This was a small attack to avenge Osama's martyrdom," a spokesman for Pakistan's main Taliban faction, Ehsanullah Ehsan, told AFP by telephone from an undisclosed location.

"Soon you will see bigger attacks. Revenge for Osama can't be satisfied just with small attacks," he said.

The umbrella group have claimed a string of attacks on the security forces to avenge the Al-Qaeda chief's killing on May 2 in an American special forces raid that apparently unfolded without the military realising.

Six guerrillas stormed the naval air base in Karachi on Sunday, killing 10 personnel and destroying two US-made aircraft each costing 36 million dollars in an attack that took hundreds of troops 17 hours to quell.

It was the worst siege on a military base since militants besieged the army headquarters in 2009, and heaped humiliation on commanders still reeling from the disclosure that Osama bin Laden had been living under their noses.

Prime Minister Yousuf Raza Gilani convened a meeting of the defence committee of the cabinet on Wednesday to review security measures, which was attended by cabinet ministers, army, navy, air and intelligence chiefs.

On the same day, nine security personnel were killed and a police station flattened in a massive suicide truck bomb in Peshawar.

"Security, defence and law enforcement agencies will be authorised to use all means necessary to eliminate terrorists and militants," the government said in a statement.

Possibly alluding to ground operations against militants along the Afghan border, it added: "All arms of the government will ensure that terrorist hideouts are being destroyed using all appropriate means."

The United States has long put pressure on Pakistan to lead a major air and ground offensive in North Waziristan, the most notorious Taliban and Al-Qaeda bastion used to launch attacks across the border in Afghanistan.

Speaking to reporters in Paris, Clinton sought to soothe tensions by saying: "It is in our national security interests to have a comprehensive long-term security partnership... with Pakistan."

The US military said Wednesday it has begun pulling some troops out of Pakistan at Islamabad's request.

A Pakistani security official said that the cuts would leave fewer than 40 Americans in the country out of "130 trainers and technical support" who had been helping to train paramilitary troops in the northwest for two years.

Militant bombings have killed more than 4,400 people in Pakistan since July 2007 as the Taliban and militants linked to Al-Qaeda wage a bloody onslaught on Pakistan's US-allied leadership.