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Britain's Muslim leaders demanded a judicial inquiry Wednesday into what motivated the four "homegrown" suicide bombers who targeted London, as Prime Minister Tony Blair (search) proposed an international conference on rooting out Islamic extremism.

The government said all 56 people known to have died in the bombings of three subway trains and a bus have now been identified, but Home Secretary Charles Clarke (search) warned that the number could rise.

Twenty-seven people remained hospitalized, several in critical condition. Police also have not ruled out the possibility of finding more bodies in the mangled wreckage of a train that is still in a deep tunnel near King's Cross station.

In Pakistan (search), an intelligence official said investigators there arrested a man who had direct links to the July 7 bombings, and investigators used telephone numbers provided by Britain to determine who may have had contact with the bombers.

Three of the bombers, all Britons of Pakistani descent, traveled last year to Karachi (search) in southern Pakistan, where officials are trying to determine whether they received training from extremists.

Blair has also sought the help of Britain's Muslim community. He met Tuesday with 25 community leaders, who have agreed to form a task force to take on the radical voice of Islam.

Sadiq Khan, a Muslim lawmaker in Blair's Labour Party, said the group was still in an embryonic stage and would address issues such as the standard of religious education, the role of the media, political participation by British Muslims and social deprivation.

Leaders warned, however, that the Muslim community alone could not eliminate extremism and called for an independent judicial probe into what may have motivated the bombers.

"The scale of disenchantment amongst Muslim youth is very clear to see," said Inayat Bungalwala of the Muslim Council of Britain. "Various factors are at play: underachievement in education; a high rate of unemployment; discrimination in the workplace; social exclusion, and also the government's own policies, especially in Iraq.

"The process of how we get four homegrown suicide bombers must be understood and that is why we are calling for an inquiry."

The demand for an inquiry appeared to reflect Muslim concerns about the impact of social problems in their communities even as they seek to distance themselves from the attacks and any form of extremism.

London's left-wing mayor, Ken Livingstone, said Wednesday that the bombers' radicalism was fueled by Western foreign policy and decades of British and American intervention in the Islamic world.

"A lot of young people see the double standards, they see what happens in Guantanamo Bay, and they just think that there isn't a just foreign policy," Livingstone told the BBC, noting however that he had no sympathy for the bombers and opposed all violence.

The U.S. Defense Department has sought to dispute allegations of mistreatment of detainees at Guantanamo, where about 520 prisoners remain, mostly Afghans, Pakistanis and others captured after the U.S. invasion of Afghanistan in 2001.

Terrorism experts have said since the London bombings that examining the suspects' mobile phone records from the months before the attacks would be a crucial part of the investigation.

The Guardian newspaper reported that a mobile phone number linked one of the July 7 suspects to a foiled terror plot last year — an alleged conspiracy to detonate a fertilizer bomb in London.

And Pakistani intelligence officials said authorities were working through some 100 telephone numbers provided by their British counterparts, checking for possible links with the suicide bombers.

Twenty of those numbers, which included both land-lines and cell phones, were still under investigation, said the officials, who did not want to be named because of the secret nature of their work.

They said Britain also provided names of several people in Pakistan who allegedly received calls from the suicide bombers over the past year. Scotland Yard declined to comment.

A point of focus in the investigation has been a religious school linked to militant groups in the eastern Pakistani city of Lahore. Security officials believe 22-year-old suspected bomber Shahzad Tanweer visited the school.

Blair said he had talked recently with Pakistani President Gen. Pervez Musharraf about tackling extremist teaching at religious schools known as madrassas — and proposed an international conference to explore the issue.

"We all know the roots of this go very, very deep," he told the House of Commons, adding the conference would focus on taking "concerted action right across the world to try to root out this type extremist teaching."

Blair's official spokesman said there was no date, venue or list of who would attend, but suggested it would include leading Muslim figures and governments from across the world.

There are about 2 million Muslims in Britain, and the overwhelming majority are moderate in their views. But extremist groups have been active in recent years, distributing inflammatory leaflets outside mosques.

Blair's government is trying to build consensus among political parties, Muslim leaders and security chiefs on how to respond to the attacks.

His top law enforcement official, Clarke, outlined anti-terrorism measures he hopes will become law by the year's end. The legislation will outlaw "indirect incitement" of terrorism, targeting extremist clerics who glorify violence and radicalize impressionable Muslim youth.

Attending terrorist training camps in Britain or abroad will be illegal, as will "acts preparatory to terrorism." Buying chemicals, or researching bomb-making on the Internet, for example, would be covered under the law.

Clarke said intelligence officials would also compile a database of suspected extremists who should be barred from entering Britain for "unacceptable behavior" such as radical preaching, running extremist Web sites and writing articles that could foment terrorism. Blair is to meet with intelligence and security chiefs Thursday to see if they require further powers.