Some UK Muslims want to fight for Taleban
The Britons were among scores of foreign volunteers who died while fighting for the Taleban in northern Afghanistan, according to the controversial Islamic group the al-Muhajiroun.
Meanwhile a Muslim community leader has accused the UK government of racism over its refusal to help a Briton captured by the Northern Alliance while fighting for the Taleban in Afghanistan two years ago.
Would-be British recruits have been warned by the government that they could face treason charges for belonging to Osama Bin Laden's al-Qaeda network - or supporting it.
The British-based al-Muhajiroun group said on Friday that Abdul Saleem, 25, from East London; Zulfikar Ahmed, 28, from Leicester; and Abu Waheed, 26, from Crawley and two others had died while fighting for the Taleban.
"Five of our British Muslim volunteers were martyred in Mazar-e-Sharif," Hassan Butt told the Associated Press news agency.
They died after the Northern Alliance seized Mazar-e-Sharif a week ago before capturing Kabul.
Racism claims
Meanwhile Shahid Malik, of Labour's National Executive Committee, has dubbed the UK government racist for failing to act on behalf of the Briton Anwar Khan, who was captured by the Northern Alliance in Afghanistan two years ago.
The 25-year-old, from Burnley, Lancashire, was taken prisoner after joining the Taleban during a trip to Pakistan.
Mr Malik, a member of the Commission for Racial Equality, said the government risked alienating British Muslims by its stance.
He argued there were countless examples of it appealing for mercy for Britons arrested abroad and cited the example of British nanny Louise Woodward.
"It seems they have one rule for white people who are imprisoned abroad and one for black people," he said.
He said no-one knew why the young man had joined the Taleban.
Family frantic
"But at that stage the Taleban was not at war with Britain and, if anything, they were allies of the West as they had been armed by the US," he added.
"His family is absolutely frantic with worry, particularly after seeing pictures of the Northern Alliance troops executing people in the street."
But a Foreign Office spokeswoman said they could not intervene in Mr Khan's case.
"This is not a simple case of someone being jailed," she said.
"It is a conflict situation and is completely different.
"Anwar Khan was fighting for the Taleban and while we have a humanitarian interest in his welfare, we cannot ask for his release."
She said the situation was rapidly changing in Afghanistan and if he was released and returned to Pakistan, for example, they would help him get documents to return to Britain.
She strongly denied any allegations of racism.
A spokesman for Prime Minister Tony Blair emphasised that there were a range of legal options available to the UK authorities to deal with British citizens who fought alongside the Taleban.