Med Crude-Urals bid at 10-year highs in south

* Urals in NWE bid to dated minus 5 cents

* Urals in south bid to dated plus 20 cents

LONDON, July 10 (Reuters) - Russian Urals firmed further on Friday in northwest Europe and the Mediterranean reflecting tight supplies of sour grades and improved arbitrage opportunities.

"Refiners are buying spot grades higher as supplies are tight in a lot of grades, not just Urals. The arbitrage is also looking workable to the east now," one physical oil trader with a European major said.

The Russian crude in southern Europe was bid at dated plus 20 cents on Friday, the highest differential in over 10 years, according to Reuters data. BFO-URL-E

URALS

* In the north, Shell withdrew a bid to dated minus 5 cents for July 20-24 cargo, traders said. That was up 25 cents on a bid on Thursday.