The night-capable, refurbished AH1-F Cobras were given to the Pakistani military by US ambassador Ryan Crocker at a military base near Islamabad, it said in a statement.

The choppers will increase Pakistan's current fleet of 19 Cobras, which were also acquired from the US, it said.

Crocker commended Pakistan's role in the "war on terror" and said that the helicopters were important weapons in "our common fight against terrorism."

"We understand and appreciate the very real sacrifices that Pakistan is making in the war on terror. The majority of important al-Qaeda arrests have occurred because of Pakistan's cooperation," he said.

The handover was part of a 50-million-dollar foreign military sales programme that would provide the Pakistan Army with 20 refurbished helicopters, the US embassy statement added.

The sale of F-16s to Pakistan late last year and the delivery of these Cobra helicopters demonstrated the long-term commitment of the United States to "all aspects of our strategic partnership with Pakistan," Crocker said.

Pakistan has posted 80,000 troops along its western border to combat Taliban and al-Qaeda militants who are crossing into Afghanistan to launch attacks on Nato and US-led forces.

However President Pervez Musharraf said Friday that he was aware of incidents in which some members of the security forces had "turned a blind eye" to insurgent movements.