British and FBI officials investigating the London terror attacks have focused on an Egyptian-born chemist who studied in the United States and an 18-year-old Briton of Pakistani descent believed to have set off the bomb aboard a red double-decker bus.

Security forces in camouflage searched the Beeston area of the northern city of Leeds as police tried to crack the network thought to have given the dead suspects planning, logistical and bomb-making support.

News reports said British authorities were seeking a Pakistani Briton with possible ties to al-Qaida followers in the US.

They said he may have organized the attacks and chosen the targets, leaving Britain the day before the July 7 bombings.

FBI agents in Raleigh, N.C., joined the search for the chemist, Magdy Asi el-Nashar, a 33-year-old former North Carolina State University graduate student. The doors were locked Thursday at the building at Leeds University where he recently taught chemistry.

And in a further international development in the inquiry, Jamaica's government said it was investigating a Jamaican-born Briton as one of the bombers.

Britain paid tribute Thursday to those killed in the attacks with two minutes of silence.

Queen Elizabeth II stood motionless outside Buckingham Palace and a crowd, many wiping away tears and bowing their heads, filled Trafalgar Square.

Source: CRI news