MOSCOW, Sept 25 (Reuters) - The Russian government has approved some changes to its fuel export ban, lifting the restrictions for fuel used as bunkering for some vessels as well as diesel with high content of sulphur, a government document showed on Monday.

It also lifted restrictions on the export of fuel already accepted for export by the Russian Railways and Transneft before the initial ban had been announced last week.

The ban on all types of gasoline and high-quality diesel remains in place.

Russia announced on Thursday that it had temporarily

banned exports

of gasoline and diesel to all countries outside a circle of four ex-Soviet states with immediate effect in order to stabilise the domestic market.

Russia in recent months has suffered shortages of gasoline and diesel. Wholesale fuel prices have spiked, although retail prices are capped to try to curb them in line with official inflation.

The crunch has been especially painful in some parts of Russia's southern breadbasket, where fuel is crucial for gathering the harvest. A serious crisis could be awkward for the Kremlin as a presidential election looms in March. (Reporting by Vladimir Soldatkin Editing by Gareth Jones)