Firefighters and police tackling the blaze at Yarlswood asylum detention centre last month say they were blocked from entering the building by staff from Group 4, the private security firm that runs the centre.

Fire Brigade representatives claim there was a "potentially catastrophic" delay of at least an hour when officers were barred from the site-NOT by detainees, as reports claimed, but by Group 4.

Bedfordshire Fire Service confirmed there had been no reports of officers being intimidated by detainees when thety entered the burning building on February 14th. 21 detainees have been missing since the night of the fire.

The claims contradict the account given to MPs by David Blunkett last Monday when the Home Secretary said: "The fire service was unable to tackle these blazes because detainees prevented it from gaining access to the buildings."

Mick Syme, secretary of Bedfordshire Fire Brigades Union, said: "We are very disappointed by what Blunkett has said: this is all about demonising the enemy. We've heard no stories of firefighters being threatened. The reality is that when officers entered the building there were a few frightened detainees running around because Group 4 still hadn't regained control."

A Bedfordshire Fire Services spokeswoman confirmed that officers were denied access to the site for an hour.

Bedfordshire Police also claim they were denied access to the site.

A Home Office statement to the Observer strongly denied the claims from police and fire officers that they had been hampered from entering Yarls Wood: "There is no question that immediate action would not be given to emergency services if their attendance was necessary."

John Bates of Group4 said:" Investigations underway will determine the chronology of events. I wouldn't like to say anything to pre-empt that enquiry".