UPDATE 1-Iran-Turkey gas flow halted after blast - source

ANKARA, May 26 (Reuters) - The flow of Iranian natural gas to Turkey was halted early on Monday after an explosion hit a gas pipeline in Turkish territory, a Turkish energy ministry official told Reuters.

"There is a good chance that the cause of the explosion on the pipeline was sabotage. The explosion occurred 13 kilometres (8 miles) inside Turkish territory," said the official.

Iran accounts for more than 20 percent of Turkish natural gas imports, though supplies from Tehran are often cut in the winter months as Iran has had difficulty covering its own supply needs.

Gas was cut last winter for nearly three weeks after Turkemenistan turned off the tap to the Islamic Republic causing a domino effect as Turkey had to stop its gas exports to Greece.

Bomb blasts are not uncommon in Turkey, where radical groups ranging from Kurdish separatists to militant Islamists and far-leftists are active. (Reporting by Orhan Coskun, Editing by Peter Blackburn)