This comes after numerous anti-aircraft rounds were fired at one of the drones on Sunday. The United States blamed pro-Russian rebels for that attack.
The unmanned aerial vehicle (UAV) – deployed to help monitor the ceasefire between government forces and separatists – was not hit and it later landed safely, the Vienna-based OSCE said.
In regard to Tuesday’s incident the OSCE said in a statement that “initial analysis of the SMM UAV flight log data indicated that the SMM UAV was subjected to military-grade GPS jamming… The SMM UAV left the area and landed safely.”
It added that this is the third serious interference with the movement of the drone and is “an impediment to the fulfilment of the Mission's mandate”.
The drones are part of an OSCE mission that was initially deployed in March under a mandate approved by the OSCE's 57 member states, including Russia.
More than 4,000 people have been killed in the six-month conflict. Ukraine and the West have accused Russia of sending weapons and soldiers to help the rebels, a charge Moscow denies.
The OSCE deployed unarmed observers in March to help ease tension. It started using drones last month and now has two in operation, though only one is used at any given time. Two more will arrive shortly, a spokesman said.