The Auschwitz-Birkenau Foundation has called on Gordon Brown to fulfill his promise to donate some of the £110m needed to save the former concentration camp from decay and ruin.

The camp has been built on marshland between two rivers and damp is seeping into the barracks, which are rotting and splintering.

Restoration experts have warned that the camp has less than two years before some parts are beyond repair.

In early December, the infamous ‘Arbeit Macht Frei’ sign was stolen by vandals, highlighting the vulnerability of the site.

Director-General of the Auschwitz-Birkenau Foundation Jacek Kastelaniec, who has visited Gordon Brown today, said: “In ten years there will be no witnesses and it will be easier for the crazy people who say nothing happened in the camps. Only the buildings will remain.

“Nobody could have imagined such a horrific act of vandalism [as the theft of the sign]. Now try to imagine the public outcry if one of the barracks started to fall down, impossible to restore.”

Gordon Brown, who visited the camp in April 2009 has pledged to contribute to the restoration but has yet to announce a figure. The government is thought to be considering donating up to £10m.

Karen Pollock, Chief Executive of the Holocaust Educational Trust, commented: "We welcome the British Government’s commitment to supporting the site’s preservation – because as the number of Survivors able to speak about their experiences dwindles, it is more essential than ever that people be given the opportunity to bear witness in person to the horrors that took place there."

Germany’s Chancellor Angela Merkel has already agreed to contribute half of the costs to restore the camp, but Mr Kastelaniec said he is keen to convince other countries that contributing is not an act of guilt but about the future.

He is planning to visit France, Belgium and the US to ask for donations and the Polish Prime Minister has sent pleas to 40 states.