MOSCOW, March 19 (Reuters) - Russia will increase oil exports through its western ports in March by almost 260,000 barrels per day (bpd) against an initial monthly plan to 2.22 million bpd after a fall in processing at refineries hit by Ukrainian drones, two trade sources said on Tuesday.

The increase - which follows an upward revision reported by Reuters on Monday - means Russia's oil shipments on a daily basis will rise by 13% in March from the initial plan, Reuters calculations show.

The sources told Reuters that two 730,000-barrel Urals oil cargoes were added to the loading plan from the Baltic ports in March by Lukoil and Rosneft, whose refineries were among those struck by Ukrainian drones last week.

"Attacks will likely reduce Russian crude runs by up to 300,000 barrels per day, in addition to scheduled maintenance closures," JP Morgan analysts said in a note.

Traders expected more possible additions to the oil export plan over the coming week as oil companies estimate actual time they have to spend on refinery repairs and if any new attacks happen.

(Reporting by Reuters; Editing by Emelia Sithole-Matarise)