The group were transferred to Cardiff from Harmondsworth centre

Refugee groups in south Wales have demanded the group of 11 be released immediately.

In 2001, widespread criticism forced the Prison Service to reverse its policy of housing asylum seekers in the jail.

The Home Office said this was a "temporary situation".

It promised the group "would not be accommodated with convicted prisoners".

David Blunkett can't blame tabloid newspapers for their coverage of asylum seekers when he behaves like this Keith Best, Immigration Advisory Service

They were transferred from the Harmondsworth Immigration and Removal Centre near Heathrow following disturbances there last month after a detainee committed suicide.

The Reverend Aled Edwards from the Cardiff Asylum Network, who is in contact with the detainees, told BBC Wales: "They were telling me yesterday they had been there for three weeks already and may be there for another four weeks."

About 30 asylum seekers kept at the jail in 2001 held a week-long hunger strike in protest at being detained there .

Assembly Social Justice Minister Edwina Hart said: "While this is not a devolved matter, the Welsh Assembly Government has contacted the Home Office previously on the detention of asylum seekers at Cardiff Prison.

"We were made aware only yesterday that asylum seekers are once again being detained at the prison.

"I have written to the Home Office seeking clarification of the reasons for their detention."

'Public prejudice'

Keith Best of the Immigration Advisory Service said it was a matter of "grave concern".

"These people have committed no criminal offence.

Asylum seekers were previously held in prison in 2001

"The home secretary gave a commitment that asylum seekers would not be held in prisons.

"There are obviously problems with the Harmondsworth centre, but we don't know how long it will take to get that back up and running properly," he said.

"The government is feeding public prejudice, and certain sections of the media, with its mentality that asylum seeker equals criminal.

"David Blunkett can't blame tabloid newspapers for their coverage of asylum seekers when he behaves like this."

The Refugee Media Group in Wales said the detainees had not been charged with a crime and should not be in prison.

In a statement, it said: "We regret the Home Office decision to detain them in this manner.

"[We] call for their immediate removal from Cardiff Prison to a more appropriate place where access to immigration and legal advice is more readily available and where they can have contact with their families."