(Reuters) - Iran on Sunday shut its border crossings with Iraq's Kurdistan in support of measures taken by the Iraqi government to isolate the Kurdish region, the Iraqi foreign ministry said.

"At the request of the Iraqi government, the Islamic Republic of Iran closed today the border crossings with the Kurdistan region of Iraq,'' the Iraqi foreign ministry said in a statement in Baghdad.

Earlier in the day, Iranian Foreign Ministry Spokesman Bahram Qassemi had indirectly dismissed claims these crossings were shut. ''As far as I know, nothing new has happened in this area,'' the Iranian Students' News Agency (ISNA) quoted him as saying.

An Iranian MP Mohammad-Javad Nobandegani said Tehran did not want to publicize the closing of the border. "There is no need for explicit publicity," the MP was quoted as saying by Iran's ILNA news agency.

The closure would negatively impact residents who depend on border trade, he said, adding that ''national interests sometimes require us to act this way."

Iran last month halted flights to and from Kurdish regions in northern Iraq over the independence referendum by the autonomous Kurdistan Regional Government (KRG).

Tehran also carried out war games at the Kurdish border in September. Tehran fears the spread of separatism to its own Kurdish population, which is around 8 million.

Iran backs Shi'ite groups which have been ruling or holding key security and government positions in Iraq since the 2003 U.S-led invasion which toppled Saddam Hussein.