"I … appeal to the government of Iraq to extend this deadline in order to permit adequate time for a solution to be found," the UN envoy to Iraq, Martin Kobler, told the UN Security Council on Tuesday.
Iraq has insisted that it is determined to close down the terrorist base by the end of 2011.
Baghdad considers Camp Ashraf and its suspected terrorist residents as a threat to its national security.
"We have already made it clear about closing ... Camp Ashraf before. The decision will be implemented by the end of this year," Iraqi Foreign Minister Hoshyar Zebari said at a news conference on October 31.
"The government insists on completing this mission ... There is no government that would agree to an organization staying against its (authorities') will, laws and sovereignty," he added.
MKO is responsible for a series of terrorist attacks inside Iran that killed a large number of Iranians, including ordinary civilians as well as high-ranking government officials.
The group fled Iran in early 1980's and was formally granted refuge and a military establishment inside Iraq in 1986 by Iraq's former dictator Saddam Hussein, who had waged a US-sponsored eight-year war against Iran in 1980. MKO's military base Camp Ashraf was then set up in Diyala Province, near the Iranian border.
The organization is also known to have cooperated with Saddam in suppressing the 1991 uprising in southern Iraq and the massacre of Iraqi Kurds.
Iran has repeatedly called on the Iraqi government to expel the group, but the US has been blocking the expulsion by mounting pressure on the Iraqi government.
The group has been officially recognized as a terrorist organization by Iran and much of the international community.