Pakistan's foreign ministry said on Friday that arrests made in Pakistan had triggered arrests in Britain on August 9 and 10.

It named British national Rashid Rauf as a "key person" who had been arrested in Pakistan.

The Britons, both of Pakistani descent, were seized last week and provided vital information that helped to expose the plot while five local "facilitators" were arrested separately, officials said.

John Reid, the British home secretary, thanked Pakistan for its  assistance after the arrests, which Islamabad said were part of a co-ordinated operation with British and US intelligence.

A senior Pakistani government official said on condition of anonymity said one of the suspects was arrested in Karachi and another in Lahore.

Al-Qaeda link

"Both the men were British nationals of Pakistani origin and were key members of the Britain-based network of militants," he said.

Another security official said that at least three of the people arrested in Pakistan had links to al-Qaeda.

US officials say the plot to allegedly bring down as many as 10 aeroplanes in a near simultaneous strike was suggestive of an al-Qaeda operation.

The authorities were also investigating some financial transactions made by an unnamed foreign Muslim welfare group to at least a dozen branches of banks in Karachi and northwestern Peshawar city, a security official said.

Khursheed Kasuri, the foreign minister, said on Friday that the suspects "had been monitored for quite some time" before they were arrested.

Pakistani intelligence officials said they expected more arrests would follow.

British authorities arrested 24 people on 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".

Pakistan came under pressure after the July 7, 2005 attacks on the London transport system when it emerged that three of the four men who killed themselves and 52 other people, were British Muslims of Pakistani origin and had attended Islamic religious schools, or madrassas, in Pakistan.