Russia blocks monitoring of more Ukraine border checkpoints - U.S.

VIENNA (Reuters) - Russia has refused to increase international monitoring of the border with Ukraine, the United States said on Wednesday, after European security watchdog OSCE extended its observers' existing mandate at two checkpoints by a month.

Ukraine and the West have accused Russia of sending weapons and soldiers to help pro-Russian separatists in the country's east, a charge Moscow denies. More than 3,700 people have been killed in fighting since April in eastern Ukraine.