That puts Murban's OSP premium to Dubai quotes at $3.56 a barrel, up 31 cents, the highest in 23 months.

The rise in premiums for light grades Murban and Das was higher than expected, trade sources said.

Most of the Murban cargoes traded last month at premiums of 20-25 cents, they said.

The following table shows the latest OSPs and their differentials to Dubai quotes in brackets.