Pakistan president Pervez Musharraf [Images] has said any unauthorised incursion by United States forces into Pakistan to pursue Al Qaeda [Images] militants would be treated as an invasion, warning that US-led coalition forces in Afghanistan would 'regret' such a misadventure.

"The United States seems to think that what our army cannot do, they can do. This is a very wrong perception. I challenge anybody to come into our mountains. They would regret that day," Musharraf said in an interview to Straits Times.

The New York Times had reported that Washington was considering granting the Pentagon and CIA new authority to conduct more aggressive covert operations in Pakistan's tribal areas where Al Qaeda is believed to be gaining strength.

Asked if any unauthorised incursion by US forces would be considered an invasion, Musharraf replied, "Certainly. If they come without our permission, that's against the sovereignty of Pakistan".

Musharraf, however, said when it comes to Al Qaeda chief Osama bin Laden, "The methodology of getting him will be discussed together and we'll attack the target together".

"Any action against him will be free, if we know where he is, if we have good intelligence," he said.

The president said US forces alone would fare no better than their Pakistani counterparts in the rugged terrain.

"Here it's a mountainous terrain. Minimal communications infrastructure. Every individual has a weapon and each tribe has its own armoury and they don't like intrusions into their privacy at all," he said, adding, "It's better if they ask some military or intelligence commander of their own whether their army, their people, coming into our mountains will operate better than our army".