MOSCOW, Oct 19 (Reuters) - Russian wholesale prices of gasoline, which is still banned for export, declined on Thursday, while diesel prices rose after sliding the previous day.

Gasoline Ai-92 grade prices declined by 1.85% on the day to 51,678 roubles ($532.69) per metric ton, data from the St Petersburg International Mercantile Exchange (SPIMEX) showed.

Diesel prices rose by 1.19% on the day to 57,163 roubles per metric ton, the exchange data showed.

Russia's fuel export ban led to an 80% fall in railway exports of gasoline in the first 15 days of October from the same period in September to some 37,000 tonnes, data provided by two market sources and Reuters calculations showed.

Russia temporarily banned exports of gasoline and ultra-low sulphur diesel (ULSD) from Sept. 21 to cope with a domestic market shortage.

The restrictions, which were eased earlier this month, made an exception for fuel supplied under inter-governmental agreements, including with members of the Moscow-led Eurasian Economic Union. ($1 = 97.0125 roubles) (Reporting by Reuters; Editing by Kevin Liffey)