The Home Office believes the hack-saw blade was sent in the post

The Sri Lankan men, in their 20s and 30s, fled from the Haslar Immigration Detention Centre in Gosport, early on Sunday.

The men, who have all had their asylum applications turned down, escaped after scaling a 20-foot perimeter fence at the centre, topped with razor wire.

The Home Office has said it believes the hack-saw blade used by the detainees to break out of the centre was sent to them in the post.

Sri Lanka is not a safe place to which to be returned and many of the men are desperately afraid Haslar Visitors Group

Hampshire Police said the men were all being held while waiting to appeal against deportation but are not considered dangerous.

It is thought they sawed through bars on the window of the room where they were being kept before climbing out to the perimeter fence.

Police believe they then threw a blanket over the razor wire, climbed up and escaped.

The Haslar Visitors Group, which campaigns for the rights of detainees at the centre, said the escape demonstrated how desperate the men were.

A spokesman for the independent charity said: "Sri Lanka is not a safe place to which to be returned and many of the men are desperately afraid."

Hunger strike

He added that until June, asylum seekers who had their application to stay in Britain refused could appeal the Home Office decision in court.

"Now they are sent back to their own country and told to appeal from there.

"They are only held in Haslar while travel documents are being obtained and not, as Hampshire Police have said, pending appeal."

Earlier this year several inmates at the centre started a brief hunger strike in protest at being kept in what they claimed were bad conditions.

In April, the centre was strongly criticised by prison inspectors for failing to make inmates feel safe.