Museum authorities at the former Nazi German Auschwitz-Birkenau death camp in Poland are struggling to save the enduring symbol of the Holocaust from the impact of time and the elements.

In the drive to stop the site falling into ruin and preserve the memory of the 1.1 million overwhelmingly Jewish victims who died here during World War II, they face tall odds.

"This is our last chance," warned Piotr Cywinski, director of the state-run museum.

The museum keeps going thanks to the Polish government, which covers around half of its costs, plus visitors' ticket fees. Up to five percent of its budget comes from the US-based Lauder Foundation and Germany's regional governments.

Last month it announced plans for a 120-million-euro (162-million-dollar) appeal to enable it to become self-financing.

Crucially, said Cywinski, it could then set aside some 5.0 million euros a year for conservation work.

The rudimentary buildings of the camp's Birkenau site, built by the prisoners on marshy land, are being battered by soil erosion and water damage.

"We have to finish conservation work on all these buildings within 10 to 12 years, so we need to start within three years at the latest," said Cywinski.

"The primary goal is to preserve the site's authentic nature and not to rebuild it, in order not to change the perception of this place," he added.

The museum devotes much of its time protecting the intimate traces of the prisoners' presence.