Med Crude-Refining margins shoot up, diffs firm

* Urals firms in Mediterranean, NWE

* Refining margins rise sharply

* Kuwait, Iraq official selling prices emerge

LONDON, Nov 12 (Reuters) - Urals differentials firmed sharply on Thursday despite thin market activity as refining margins rose to above their one-year average, traders said.

"Urals trades are very thin at the moment," one trader said.

Iraq raised the official selling price for Basra light crude to U.S. buyers for December by 25 cents to $4.70 below the WTI benchmark, the State Oil Marketing Organisation said on Thursday. [ID:nRAS228842]

Traders said Kuwait had lowered its December official selling price for its Asia-bound crude, loosely linked to Saudi Arabia's Medium Grade, by 15 cents to 85 cents below the average of Oman/Dubai quotes. [ID:nT374291]