MOSCOW, May 31 (RIA Novosti) - Units of Russia's Railroad Troops have started rebuilding railroad infrastructure on the territory of Georgia's breakaway region of Abkhazia under a presidential decree on humanitarian aid to the self-proclaimed republic, the Defense Ministry said on Saturday.

"In accordance with the Russian president's decree on humanitarian aid to Abkhazia and a request by the Abkhazian authorities, units from the Russian Railroad Troops and special non-military equipment have been dispatched to rebuild railroads and infrastructure [in Abkhazia]," the ministry said in a statement.

Abkhazia and South Ossetia, another breakaway region in Georgia, have been a source of tensions between Russia and Georgia, with Tbilisi accusing Moscow of backing separatism on its sovereign territory.

Relations between Moscow and Tbilisi have drastically deteriorated since Russia's former president Vladimir Putin called for closer ties between Moscow and the two breakaway republics in mid-April.

Georgia has accused Russia of trying to annex Abkhazia and South Ossetia, while Moscow says Tbilisi is planning to invade Abkhazia.

Bilateral relations saw a new low this week when the Georgian Foreign Ministry demanded that Russia give an official apology and pay compensation following the alleged shooting down of an unmanned reconnaissance drone by a Russian aircraft in April.

Ex-Soviet breakaway regions have stepped up their drive for independence since Kosovo's declaration of independence on February 17. Abkhazia and South Ossetia, along with Moldova's Transdnestr, have since asked Russia's parliament, the United Nations and other organizations to recognize their independence.