Witnesses say armed security forces surrounded the car of Cambodia's No. 2 opposition leader in an apparent attempt to apprehend him.

Opposition leader Sam Rainsy said police also entered the Cambodian National Rescue Party headquarters looking for his deputy, Kem Sokha. He was, however, not in the car or at the headquarters, and the policemen left empty-handed.

The crackdown Thursday came hours after the Sam Rainsy criticized the government's plans to hold elections next year. He said the polls would be neither free nor fair since Prime Minister Hun Sen has thrown several opposition members and rights activists in jail.

CNRP spokesman Yim Sovann said Kem Sokha's car was stopped on a Phnom Penh street by a group of special police force members brandishing guns.