Moscow - Russian president Dmitry Medvedev spoke by telephone with his Georgian counterpart Mikheil Saakashvili on the latter's opposition to Russian support for Georgia's rebel region of Abkhazia, the Kremlin said Tuesday.

The Georgian side initiated the talks, according to the Kremlin, after demanding the immediate withdrawal of over 300 Russian troops deployed in Abkhazia to repair its railway lines - a move Tbilisi called "yet another step towards annexation."

"The question of Russia's aid in repairing Abkhazia's rail tracks was raised during the conversation ... Satisfactory explanations were given on this count," the Kremlin said in a statement posted on its website Tuesday.

Russia's Foreign Ministry on Tuesday defended sending a unit of Russian Railway Forces to Abkazia, stressing these were unarmed military engineers.

In a statement Tuesday the ministry shrugged off Georgia's objections as "a new wave of anti-Russian fuss," saying the rail work was being undertaken under a 2003 agreement with Tbilisi for the resumption of rail routes via Abkhazia.

The two heads of state are set to meet later this week on the sidelines of an economic forum in St Petersburg on June 6-7.

Long simmering tension erupted last month when Russia announced it was strengthened diplomatic ties and its peacekeeping presence in Abkhazia in what analysts see as a response to Georgia's aspirations to join the North Atlantic Treaty Organization (NATO).

Last month, Russia claimed it had intercepted a Georgian spy helping rebel cells in the Caucasus, while Georgia accused Russia of shooting down one of its reconnaissance flights.

The escalating accusations were addressed at a session of the UN Security Council last week following a UN report corroborating Tbilisi's claims that Moscow was behind the shooting of its drone.

After the Security Council talks, the United States expressed dismay over Russia's announcement of troop increases in Abkhazia without the consent of the Georgian government.

Russia has had some 2,500 peacekeeping troops in Abkhazia since a ceasefire ended civil war in 1994, and most residents of the autonomous region have held Russian passports since 2000. (dpa)