Three armed men attacked and robbed a U.N. observation post on the Iraqi side of the Kuwait-Iraq border, the United Nations said Sunday.

Saleem Fahmawi, spokesman for the U.N. Iraq-Kuwait Observation Mission, said three intruders armed with AK-47 rifles and a pistol broke into the observers’ rooms early on the morning of March 23.

No one was hurt.

On Thursday, Iraq said it had arrested six Iraqis who confessed to spying for Kuwait. It said they had been ordered to attack U.N. personnel on the border so Iraq would be blamed.