"The purpose of the visit is to provide the Russian side with an accurate overview of the situation in Lebanon," the Lebanese ambassador to Russia, Assem Jaber, told RIA Novosti.
At the same time, Lebanese media have said it was unclear whether the critical situation in the country would permit the head of government to leave.
Siniora has been under enormous pressure by the pro-Syrian opposition to resign, with mass anti-government demonstrations in the center of Beirut running into their second week.
The Shiite radical groups Hizbollah and Amal, in alliance with Christian leader Michel Aoun, have accused the Siniora government of doing the West's bidding, and have demanded that Shiites be given enough Cabinet seats to wield veto power.
The latest wave of protest comes in the wake of the November 21 assassination of the anti-Syrian politician Pierre Gemayel, who served in Siniora's government as industry minister.
Gemayel, 34, was killed when his car was raked by gunfire on a Beirut street. Two years ago, the so-called "Cedar Revolution" drove Syrian troops out of Lebanon following the assassination of another anti-Syrian politician, Prime Minister Rafik Hariri, who had called for an end to Syria's long-standing occupation of the Mediterranean country.
Syria has denied involvement in either killing.