ISLAMABAD - Pakistan on Thursday promised US Secretary of State Condoleezza Rice that it would take "strong action" against anyone on its territory found to have been involved in the Mumbai attacks.

President Asif Ali Zardari told the top US diplomat, on a lightning visit to Islamabad, he was determined that Pakistan would not be used to orchestrate attacks or shelter terrorists such as those who committed last week's outrage.

Zardari reiterated a pledge to help probe the attacks, in which 172 people were killed, amid rising tensions with India, which has said all the attackers in the brazen assault came from Pakistan.

"The government will not only assist in investigation but also take strong action against any Pakistani elements found involved in the attack," Zardari said in an official statement issued after he met with Rice.

"Pakistan is determined to ensure that its territory is not used for any act of terrorism," he added.

Pakistan's role in the US-led "war on terror" has come under renewed focus since the devastating assault in Mumbai, which saw militants armed with guns and grenades lay siege to hotels and other sites in the city for 60 hours.

Rice flew into Islamabad Thursday in a bid to defuse tension in the region after visiting New Delhi the previous day.

"I found the Pakistani leadership very focused and committed to act," she told reporters after talks with Zardari, Pakistani Prime Minister Yousuf Raza Gilani and senior army officials.

"Everybody wants to prevent further attacks," she said.

In Washington, the White House also urged Pakistan to waste no time in cooperating with the Indian probe.

"Pakistan needs to act with resolve, urgency. They need to cooperate fully and transparently and they need to keep the line of communication open between their country and India," said spokeswoman Dana Perino.

Pakistan has been a key US ally since the September 11 attacks seven years ago, but many critics openly question whether elements in the Pakistan military and intelligence services support Islamist militants.

Suspicion has fallen on Lashkar-e-Taiba, a Pakistan-based militant group which has fought Indian control of divided Kashmir and which attacked the Indian parliament in 2001, nearly pushing the two nations to another war.

India and Pakistan have fought three wars since independence from Britain in 1947, and both countries now have nuclear weapons. A peace process between them has been slow-moving and mistrust is high.

Indian Foreign Minister Pranab Mukherjee told Rice on Wednesday that his country was considering all options in responding to the attacks.

The United States is concerned about any military stand-off with India that might see Pakistan move troops from its border with Afghanistan -- a crucial area where Taliban and Al-Qaeda fighters have been gaining ground.

The Pakistan president, however, gave no indication to Rice that any suspects on its soil would be extradited to India.

According to diplomatic sources in the Indian capital, New Delhi has demanded that Pakistan hand over 20 terror suspects, including Lashkar-e-Taiba's founder, Hafiz Saeed.

But Pakistan interior ministry chief Rehman Malik Thursday denied there was any list provided by India to Pakistan and said Saeed's name was not among three suspects sought by New Delhi.

"They gave us three names, two of them are Indian nationals -- Dawood Ibrahim and Tiger Memon -- and the third is Maulana Masood Azhar," Malik told reporters.

He said the two Indian nationals were not on Pakistani soil. India should provide evidence against Azhar so that the "law can take its own course," Malik said without elaborating.

Rice's visit came as India said on Thursday it had put all its major airports on high alert following warnings of possible attacks using hijacked airliners.