An Egyptian biochemist who studied in the United States has been arrested in Cairo in connection with the London terror attacks, officials said Friday.
Magdy Mahmoud Mustafa el-Nashar, 33, denied any role in the attacks, the Egyptian Interior Ministry said in a statement. He was taken into custody after the July 7 transit bombings and was being questioned, it said.
No charges have been filed against him.
London police confirmed that a man was arrested in Cairo, but they would not confirm his name or characterize him as a suspect in the attacks that killed at least 54 people, including four bombers.
Police in Leeds sealed off an even larger section of the city Friday after finding highly explosive triacetone triperoxide was found in the apartment. That's the same substance used by Richard Reid, the shoe bomber who was arrested in 2001.
Police also raided a shop in Leeds selling Islamic books and DVDs just blocks from where at least two of the four suicide bombers lived, and they seized materials.
Muslim leaders have said the young bombers might have been inspired by radical literature. It was not immediately clear whether any of the four bombers had links to the shop, but neighbors speculated that the owner or manager may have met the suspects there.
U.S., British and Egyptian officials had been in contact concerning el-Nashar following the blasts, according to an Egyptian government official who spoke on condition of anonymity because he was providing information not in the ministry's statement.
El-Nashar was vacationing in Egypt and had intended to go back to Britain to continue his studies, the ministry said, without specifying the date he was taken into custody.
"El-Nashar denied having any relation with the latest events in London. He pointed out that all his belongings remained in his apartment in Britain," it said.
El-Nashar recently taught chemistry at Leeds University. The school said el-Nashar arrived in October 2000 to do biochemical research sponsored by the National Research Center in Cairo, Egypt. It said he earned a doctorate May 6.
FBI agents in Raleigh, N.C., had joined the search for el-Nashar. North Carolina State University spokesman Keith Nichols said a person named el-Nashar studied there as a graduate student in chemical engineering in early 2000.
Earlier, Metropolitan Police Commissioner Sir Ian Blair said investigators were hunting the organizers of the London transit attacks — perpetrated by what he called "foot soldiers" — and confirmed police were focusing on a Pakistan connection.
Three of the bombers who carried out last week's terror strikes were Britons of Pakistani descent. Pakistani intelligence officials said Friday that local authorities are looking into a connection between one of the three and two al Qaeda-linked militant groups in that country.
Blair told the BBC that police believed they would discover an al Qaeda connection to the blasts.
"What we expect to find at some stage is that there is a clear al Qaeda link, a clear al Qaeda approach, because the four men who are dead, who we believe are the bombers, are in the category of foot soldiers," Blair said.
Authorities in Pakistan, meanwhile, were looking into a connection between one of the London suicide bombers and two al Qaeda-linked militant groups in Pakistan, including a man arrested for a 2002 attack on a church near the U.S. Embassy, two senior intelligence officials said.
The investigation is focusing on at least one trip that 22-year-old Shahzad Tanweer made to Pakistan in the past year, said the officials, who work at two separate intelligence agencies and are involved in the investigation. They spoke to The Associated Press on condition of anonymity because of the secretive nature of their jobs.
One of the officials said that while in Pakistan, Tanweer is believed to have visited a radical religious school run by the banned Sunni Muslim militant group Lashkar-e-Tayyaba.
The sprawling school in Muridke, 20 miles north of Lahore, has a reputation for hostility. Journalists who have traveled to the school in the past have been threatened and prevented from entering.
Lashkar-e-Tayyaba was banned by Pakistan for alleged links to a 2001 attack on India's Parliament.
In another international development in the inquiry, Jamaica's government said it was investigating a Jamaican-born Briton as one of the bombers. Reports identified him as Lindsey Germaine.
On Thursday, police released closed-circuit TV video showing one of the four suicide bombers — 18-year-old Hasib Hussain — wearing a backpack as he passed through the Luton train station on his way to London.
Hussain allegedly set off the bomb that killed 14 people aboard the bus. That blast occurred nearly an hour after three London Underground trains blew up, and investigators don't yet know what Hussain did during that hour or when he boarded the bus.
Trying to map out Hussain's movements, police appealed for information from anyone who may have seen him in or around King's Cross station, where the four parted ways.
Police officially identified two of the suicide bombers Thursday
Hussain and Tanweer, whom they say attacked a subway train between Liverpool Street and Aldgate stations.
News reports have identified the fourth bomber as 30-year-old Mohammed Sidique Khan.