Russia plans to boost diesel exports from its major western ports by almost a fifth next month amid growing refinery runs.

Diesel loadings from facilities on the Black and Baltic seas, including some cargoes originating in Belarus, are set to rise to 3.39 million tons in January, industry data seen by Bloomberg show.

That equals about 817,000 barrels a day, or 18% more than the nation exported in the first 28 days of December, according to calculations based on historical data from intelligence firm Kpler.

The robust plan comes as refineries increase their processing rates. In the first 20 days of this month, crude refining averaged about 5.57 million barrels a day, an increase of almost 60,000 barrels a day from November, when the planned maintenance season ended.

The plan seen by Bloomberg only shows shipments of diesel delivered to three ports by pipeline. Smaller volumes also may be sent by rail.

Actual flows may differ, depending on the weather and demand from foreign customers. Pipeline operator Transneft PJSC, which compiles the loading schedules, declined to comment.

Some restrictions remain on overseas supplies of the fuel. While Russia’s government allowed exports of summer-grade diesel, shipments of winter-grade diesel to foreign markets is allowed only if the fuel is delivered to ports by pipeline.

In addition, refiners need to keep at least 50% of their output at home.