Rosneft and Russneft failed to load some 0.22 million tonnes of crude in total from the November loading plan prior to Dec. 5 and the vessels chartered to export these volumes left Novorossiisk without them, they added.

Russian oil companies don't comment commercial operations.

The price cap for Russian oil introduced by Western countries leaves participating countries unable to provide oil transportation, insurance, financing and other services for any Russian oil cargoes sold above the price cap of $60 per barrel.

December loadings are some 2-3 days behind schedule, with adverse weather potentially causing longer delays, industry sources said.

(Editing by Kirsten Donovan)