The trip comes amid mounting fears that the US is prepared to launch military "hot pursuit" raids into Pakistan's troubled tribal belt following an upsurge in attacks against international and local forces in Afghanistan.

"It is in the interest of Pakistan to curb extremism and terrorism," Gilani told reporters before leaving on a three-day official visit, which is his first trip to the US since becoming Prime Minister in March.

Pakistan has repeatedly declared that its territory will not be used as a base for terrorism but has also warned that attacks on its soil from external forces, such as the US, will not be tolerated.

"The fight against extremism and terrorism is Pakistan's own cause," said Gilani, who will discuss with Bush stepping up efforts against Islamists who have launched attacks on NATO and US forces in Afghanistan.

"I lost my leader because of terrorism," he added, alluding to slain former premier Benazir Bhutto, who was assassinated in a gun and suicide attack during an election rally in the garrison town of Rawalpindi in December.

US military commanders have reported a 40 percent rise in militant attacks on parts of eastern Afghanistan since Pakistan's new government launched peace talks with Taliban rebels in the tribal belt.

And with Gilani's government also facing economic problems at home just five months after defeating allies of US-backed President Pervez Musharraf in elections, he is expected to come under renewed pressure from Bush on Monday.

"Gilani will have to face tough questions from US leaders as they are not satisfied with the new government's performance in curbing the insurgency," Hasan Askari, a political analyst at Johns Hopkins University in Washington DC, told AFP.

Washington, Pakistan's main ally in the "war on terror," has said it did not approve of the negotiations, which include top Taliban commander Baitullah Mehsud, who is accused of masterminding Bhutto's assassination.

"US leaders will confront Gilani with hard facts about activities of Taliban in tribal regions and will ask him to do more," Askari said.

"But at the same time, Americans would also like to dispel the impression that the new government in Pakistan does not have the support and confidence of the Bush administration," he added.

Gilani left for the US three days after the Pakistani army wound up a week-long operation in the restive northwestern district of Hangua after clearing the area of Taliban forces and killing at least 20 militants.

Gilani said that he will also exchange views with Bush and other US leaders on forging cooperation in areas of defence, education, health, science and technology, agriculture and intelligence sharing.