Pakistan's extremist Islamic leaders would gain power if President Pervez Musharraf [Images] was assassinated or replaced, a top US intelligence official told the Senate Intelligence Committee on Wednesday.

"We are concerned that the new Islamic leaders would not be pro-US," said Director of the US Defence Intelligence Agency Vice Admiral Lowell E Jacoby. He said his "assessment remained unchanged from last year."

Musharraf continues to be a key ally in the US war on terrorism and provides critical support against Al Qaeda [Images] and Taliban operating in Pakistan, noted Jacoby.

He added that the terrorist groups continue to pose a high threat to senior Pakistani government officials, military officers and US interests.

"There have been assassination attempts against the Pakistan prime minister and a corps commander since last year. Even Musharraf is at high risk, although no assassination attempts have been made on him since December 2003," said Jacoby.

Investigations of Musharraf's assassination attempts revealed complicity among junior officers and enlisted personnel in the Pakistani army and air force, he noted.