SINGAPORE- * June Brent crude's premium to Middle East benchmark Dubai quotes jumped to $2.74 a barrel on Thursday, the highest in six months, Refinitiv data showed

* The spread widened by 39 cents from a day earlier after news of Russian oil contamination drove up Brent prices

* Brent crude's premium to Dubai quotes has gained 86 percent since the start of April, data showed 

* A wider spread makes Brent-linked grades produced in the Asia Pacific and the Atlantic Basin more expensive than those from the Middle East and Russia

(Reporting by Florence Tan; editing by Christian Schmollinger and Rashmi Aich) ((Florence.Tan@thomsonreuters.com; +65 6870 3497; Reuters Messaging: florence.tan.thomsonreuters.com@reuters.net))