"The Sobibor site was closed until further notice as of June 1 as the current budget does not allow for its operation," museum spokesman Marek Bem was quoted as saying by the Polish PAP news agency on Thursday.
Cash-strapped local authorities in nearby Wlodawa had been responsible for running the site of the infamous former death camp where 250,000 Jews perished at the hands of Nazi Germany between in 1942 and 1943 in what was then German-occupied Poland.
Poland's Ministry of Culture said Thursday it expected the Sobibor site to re-open soon under its direct management after the completion of an ongoing administrative re-organisation.
"As of January 1, 2012, we foresee the creation of the Museum of Sobibor, as an autonomous institution established and funded by the Ministry of Culture," it said in a statement released on Thursday.
In the meantime, authorities said the Sobibor museum would be administered by the nearby museum at Majdanek, another former Nazi German death camp in Lublin, eastern Poland.
In a letter obtained by AFP, the American Gathering of Holocaust Survivors and Their Descendants said "Holocaust survivors are aghast that the museum at Sobibor, the site of John Demjanjuk's crimes, has closed because of insufficient funding by Polish state authorities."
Last month, a German court sentenced the 91-year-old Ukrainian-born Demjanjuk to five years imprisonment for assisting the Nazis in the killing of almost 30,000 Jews at Sobibor. Demjanjuk denied the charges and has appealed the conviction.
After an uprising at the camp in October 1943, the Nazis razed it and built a farm there in an attempt to conceal the traces of their crimes.