A Yemeni military official says the son of outgoing President Ali Abdullah Saleh is leading a crackdown within the powerful Republican Guard, which he commands, to purge it of rebellious officers.

The official says Saleh's son, Ahmed, has had dozens arrested so far. He says the crackdown seeks to prevent officers from joining mass protests against Saleh's rule. The official says Ahmed warned at a Guard meeting this week against "copying" labor strikes that are spreading across Yemen within his force.

The official spoke on condition of anonymity because of the sensitivity of the issue.

Hundreds of men in military uniforms marched on Saturday through the city of Taiz, calling for trials of top commanders over the killings of unarmed protesters during the country's uprising.