Russian crude exports from the Baltic Sea ports in May are set to fall to 6.7 million tonnes from 7.5 million tonnes in April, according to the preliminary loading schedule seen by Reuters.
Urals and Siberian Light exports from Novorossiisk will increase by 2 percent a day to 2.865 million tonnes, from 2.72 million tonnes in April, the document showed.
Russian pipeline monopoly Transneft said on Monday that it had suspended oil loadings from the Black Sea port of Novorossiisk because of a storm.
South Korea's GS Caltex, meanwhile, has bought Russian Urals crude for the first time, purchasing 700,000 barrels for delivery in June.
Oil prices slipped by about 1 percent on Monday, extending last week's decline, on lack of confirmation that OPEC will extend production cuts until the end of 2017 and as Russia indicated that it can raise output if production cuts deal lapses.
In the Platts window Shell bought from Glencore 100,000 tonnes of Urals in the Baltic for May 9-13 at dated Brent minus $1.75 a barrel, up 15 cents from Friday.
There was no activity for Urals in the Mediterranean on Monday.
In lighter grades, Itochu bid for 600,000 barrels of Azeri Light for May 4-8 up to a premium of $2.25 a barrel to dated Brent without finding a seller.
There were no buyers and sellers of CPC Blend in the Platts window.