"The reports follow claims from a former intelligence officer in Burma's ruling junta that thousands of protesters have been killed and the bodies of hundreds of executed monks have been dumped in the jungle.
The most senior official to defect so far, Hla Win, said: "Many more people have been killed in recent days than you've heard about. The bodies can be counted in several thousand."
Mr Win said he fled when he was ordered to take part in a massacre of holy men."
Burma: UN envoy meets top general as regime blames foreigners for violence