"If this has really happened, then we express our satisfaction that the Russians on board the vessel will be home soon," Foreign Ministry spokesman Igor Lyakin-Frolov said.
The Faina, with a crew of 17 Ukrainians, three Russians and one Latvian, was hijacked off the Horn of Africa on September 25, 2008. The vessel's Russian captain died of a heart attack soon after the hijacking.
The pirates initially demanded a $35 million ransom for the vessel, which was carrying 33 T-72 tanks and other heavy weaponry. However, media reports have said that the pirates were eventually paid $3.2 million to free the ship.
Lyakin-Frolov also said that the Russian Ministry had cooperated as much as possible "to free the Russian nationals."
Some media outlets earlier claimed that the intended destination for the weapons was southern Sudan's rebel Dafur region, and not Kenya as was announced. Both the Ukrainian and Kenyan authorities have denied the claims.
According to the UN, Somali pirates carried out at least 120 attacks on ships in 2008, resulting in a yield of around $150 million.
Up to 20 warships from the navies of at least 10 countries, including Russia, are involved in anti-piracy operations off Somalia. The East African country, ravaged by years of civil war, has no functioning government.