Bulgaria's Culture Minister Stefan Danailov called on Christie's auction house to stop the sale of a unique silver Byzantine plate originating from Bulgaria, Darik Radio reported.

Christie's announced that it would offer the treasure for sale on November 9 2006.

The unique plate had been found during illegal treasure-hunt excavation near the Bulgarian town of Pernik in 1999, Darik said.

Danailov sent Christie's a letter saying that the plate was exported illegally from Bulgaria.

Christie's had well-deserved authority and was famous for its policy to refrain from selling objects of unclear origin, Danailov wrote. He called on the auction house to hold back the sale at least until the plate's origin was clarified.