In comparison, medium grades were faring better, although they were not fetching strong premiums either, they added.

"The whole market is a little bit under pressure. But relatively speaking, medium grades are in better shape," one trader said.

Light grades, such as Abu Dhabi's Murban, are increasingly unpopular among Japanese refiners amid high middle distillate stocks, traders said.

No August Murban deals have been heard in the market for about a week since the last known transaction was concluded at two cents over the official selling price (OSP) last week, traders said.

The next Murban deal is quite likely to be done at a discount to the OSP, they said.

August Oman, which is medium-grade material, has largely been traded at parity to OSP, except for one recent deal at a discount of 1.5 cents, traders said.

In Yemeni crude trading, an AugustMasila cargo was rumoured to have been sold by a Canadian oil firm to a U.S. Major at $1.70 per barrel below dated Brent, compared with the August term price of $1.65 under dated Brent.