Seven of the suspects, all men, are physicians, according to the official, while the lone woman, the wife of one suspect, is a laboratory technician.

Attention is now turning to unraveling the links within the circle of doctors to determine how this network was organized.

Investigators searched two houses in Liverpool, where Shabeel Ahmed, one of the doctors allegedly connected to the plot, is believed to have been living.

Police officers in forensic suits carried out several bags of evidence, containing computer hard drives and documents.

Investigators were “at the very early stages” of trying to find out where the alleged conspirators came from, said a British official, who spoke on condition of anonymity, citing government rules.

“There are various overseas connections,” the official said, adding, “It’s possible there may be an interesting Iraqi angle.”

The possibility of links with Al Qaeda leaders in Iraq moved to the forefront after a claim made by an Anglican priest living in Iraq that he had been warned about attacks in Britain and the United States.

The priest, Canon Andrew White, said that, at a gathering of Iraqi religious leaders in Amman on April 18, one of the visiting leaders told him “those who cure you will kill you.”

He did not pay much attention to the language, White said in a telephone interview, and did not mention it to British officials when he told them about the meeting. However, when he saw that these attacks were apparently the work of doctors, he recalled what the man had said.

... contd.