Intelligence agents arrested at least seven people, including two British nationals of Pakistani origin, who provided information on an alleged terror plot aimed at blowing up U.S.-bound passenger jets from Britain, a senior government official said Friday.

The arrests were made in the eastern city of Lahore and in Karachi, Pakistan's main port on the Arabian Sea, the official said on condition of anonymity because he did not have authority to speak formally on the issue.

Two were Britons arrested a week ago and had provided information about the plot during interrogation, he said. The five Pakistanis were arrested on suspicion that they served as their local "facilitators," the official said. It wasn't clear when they'd been detained.

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He did not have know whether they had links with any local or foreign militant organization.

An official at the British High Commission in Islamabad could not confirm the arrests of the Britons, and referred questions to Pakistan's government.

Pakistan's government said Thursday it had played "a very important role" in uncovering the plot — allegedly to bring down as many as 10 jetliners in a nearly simultaneous strike that U.S. officials say was suggestive of an Al Qaeda operation.

Foreign Ministry spokeswoman Tasnim Aslam on Friday said some arrests were made in Pakistan but refused to give details. "The investigation is going on. We are not talking about their identities," she told The Associated Press.

Pakistani intelligence officials also confirmed the arrest four or five days ago of a suspect in Faisalabad, a city about 120 kilometers (75 miles) east of Lahore. They did not provide further details about the suspect's nationality or connection with the plot. They said they expected more arrests would follow.

That arrest appeared to be different to the seven made in connection with the alleged terror plot.

British authorities arrested 24 people Thursday based partly on intelligence from Pakistan. The suspects were believed to be mainly British Muslims, at least some of Pakistani ancestry.

A Pakistani intelligence official said an Islamic militant arrested near the Afghan-Pakistan border several weeks ago provided a lead that played a role in "unearthing the plot." The official spoke on condition of anonymity because of the sensitivity of the issue.

Pakistan, a key ally of Britain and the U.S. in the war on terrorism, has been long been regarded as a center of Islamic militancy.

Three of the four suicide attackers in the July 7, 2005, bombings on the London transport system that killed 52 people were British Muslims of Pakistani origin and had visited Pakistan before the attacks.

One of the bombers visited a pro-Taliban seminary run by the hard-line Jamaat al-Dawat group in the eastern city of Lahore before the blasts, but officials in Islamabad say none of the London bombers received militant training or support during their visits.

Pakistan placed the hard-line group's leader, Hafiz Mohammed Saeed, under house arrest on Thursday for a month in Lahore, but officials said it wasn't linked to the aircraft plot. Lahore police chief Khawaja Khalid Farooq said authorities feared Saeed's plans to address a rally Saturday could lead to unrest.

On Friday, Pakistan stepped up security at airports, preventing hand-carried luggage on all flights. However, state carrier Pakistan International Airways reported no delays and said a flight would depart on schedule for London's Heathrow airport around midday.

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