LONDON, Dec 3 (Reuters) - Northwest European diesel profit margins softened by about 50 cents to $17.80 a barrel on Tuesday on expectations that Russian supplies will rise this month.

• In the Platts window, Aramco Trading and TotalEnergies sought ULSD cargoes in the Mediterranean for a second consecutive session, while Petroineos posted an offer. A Gunvor offer was at front month diesel futures +$13 a barrel was withdrawn. In the Mediterranean high-sulphur gasoil cargo market, Bayegan again sought a cargo, without attracting any selling interest. Gunvor offered a UK winter grade cargo for Amsterdam delivery.

• Russia's exports of ultra low-sulphur diesel (ULSD) from the Baltic Sea port of Primorsk are set to rise by 23.2% in December to 1.4 million metric tons from 1.1 million scheduled for November, two traders said on Tuesday.

• Diesel exports are increasing on rising fuel production as seasonal maintenance — and unplanned work — on refineries was completed, market sources added.

• Russia expects to have 1.1 million tons of refining capacity offline in December, down from 2.4 million in November, Reuters calculations based on data from industry sources show.

• Meanwhile, EU and UK diesel and gasoil imports are forecast to reach about 833,000 barrels per day (bpd) in December, according to Kpler, compared with 1.03 million bpd last month.

(Reporting by Ahmad Ghaddar; Editing by Alan Barona)

((Ahmad.Ghaddar@thomsonreuters.com; +442075424435; Reuters Messaging: ahmad.ghaddar.thomsonreuters.com@reuters.net))