President Asif Ali Zardari yesterday welcomed the new US strategy in the war on Islamist militants as a "positive change" and vowed to prevent Pakistan being used for terror activities.

"I welcome President (Barack) Obama's call to the Congress to pass the bill for the $1.5 billion aid to Pakistan in a year," he said in a keynote speech to parliament, reiterating comments he made late Friday.

"The US presidency's approach now represents a positive change. It is an endorsement of our call for economic and social uplifts as a means to fighting extremism," Zardari added.

Obama on Friday put Pakistan at the centre of the fight against Al-Qaeda in unveiling a new strategy to commit thousands more troops and billions of dollars to the Afghan war and tripling US aid to Pakistan.

"Pakistan must demonstrate its commitment to rooting out Al-Qaeda and the violent extremists within its borders," the US president said, throwing down the gauntlet to the nuclear-armed nation.

"The government will not allow the use of its soil for terrorist activities against any other country even as we will also not allow anyone to violate our sovereignty," Zardari said.

"(The) sovereignty of Pakistan must be protected at all costs."

Obama's speech made no mention of US drone attacks targeting Al-Qaeda and Taliban militants in Pakistan - raids the government bitterly opposes as a violation of its sovereignty and which have killed more than 340 people since August 2008.

Zardari said the government had adopted a three-pronged strategy to deal with militancy which included dialogue with peaceful elements, the use of force against gunmen and economic help for the tribal regions.

"The strategy is based on making peace with those willing to give up violence. But at the same time to deal firmly with those who challenge the writ of the government," he said.

"It also aims at economic development of the affected areas."

Zardari said his government had set up a national Counter-Terrorism Authority and with the help of friendly countries it would raise an additional police force of 20,000 in four provinces with special equipment.

He also paid tribute to hundreds of Pakistani soldiers, police and citizens who have been killed in suicide bombings and attacks by Taliban militants.

"The nation is proud of the sacrifices of the members of the armed forces, paramilitary forces, police and citizens in enforcing the writ of the government.