Four male staff, who are understood to have been working on a programme for the current affairs series Spotlight, were among 11 men arrested over Saturday and Sunday.

The corporation made clear the reporters, who were released late last night, had been working on a current affairs programme and had full editorial authoristaion "under the BBC's guidelines".

East Londonderry DUP MP Gregory Campbell asked the BBC to explain what the guidelines were, and what the broadcasting team were doing when they were seized.

Gardai were last night still questioning the seven remaining men, being held under Section 30 of the Republic's Offences Against the State Act.

A garda spokesman said the men are aged between 30 and 48.

"The arrests relate to ongoing investigations into paramilitary activity," he added.

In a statement released last night a BBC spokesman said: "We can confirm that some of those arrested in Co Donegal were BBC journalists.

"They were working on a BBC Northern Ireland current affaiars investigation and had full editorial authorisation under the BBC's guidelines.

"The other parties present were fully aware that they were with BBC journalists."

But Mr Campbell last night called on the BBC to inform the public as to what the guidelines were.

"I would like to hear the BBC expand on that and say what it was exactly they were doing.

"They need to: A, explain what their guidelines are, and B, explain the activities of the camera crew when gardai took steps against them."

He added: "It's all very well for them to say they have guidelines but the public need to know what these are."

Irish secretary for the National Union of Journalists Seamus Dooley confirmed the men arrested were NUJ members.

He said: "We would be confident the BBC would uphold the right of their journalists to protect confidential sources of information."

BBC journalists arrested in Garda probe