A Briton said to have been held in Pakistan over the London terror attacks reportedly had telephone links with two of the suicide bombers.
Haroon Rashid Aswat is thought to have been brought up in Dewsbury, the same area of West Yorkshire as Mohammad Sidique Khan.
Reports quoting intelligence sources said that Aswat had been arrested in Pakistan, but this was denied by Pakistani officials.
Security sources told newspapers the alleged al-Qaeda planner had up to 20 conversations with Khan and another of the bombers, Shehzad Tanweer, one just hours before the blasts.
One newspaper claims he entered the UK through Felixstowe, Suffolk, two weeks before the attacks, and left on a flight from Heathrow hours before the carnage.
According to reports, he was arrested in a raid at a religious school, or madrassa, in Sargodha, wearing an explosive belt and carrying thousands of pounds in cash.
He is thought to have stayed at the madrassa with two of the suicide bombers.
A senior Pakistani source said: "We believe this man had a crucial part to play in what happened in London."