VIENNA (REUTERS) - European security watchdog OSCE said on Tuesday it had lost contact with one of its teams of monitors near the town of Donetsk in eastern Ukraine, where pro-Russian militants are clashing with Kiev government forces.

The four-strong international team was on a routine patrol east of Donetsk when contact was lost on Monday evening, the Organisation for Security and Cooperation in Europe said.

"We have been unable to re-establish communication until now," it said in a statement.