CARACAS (Reuters) - Former European champions Russia and Lithuania have claimed two of the last three remaining berths in the men's basketball tournament at the 2012 London Games following their victories in the semi-finals of the ongoing Olympic qualifying tournament.

The Russians overcame a stiff challenge from Nigeria to beat the west African nation 85-77 while Lithuania blew away the Dominican Republic 109-83 in the fiercely competitive 12-team tournament in Venezuela on Saturday.

The Nigerians and the Dominicans, who have been surprise packages in the event, will lock horns for the remaining Olympic slot.

The United States, Spain, France, Argentina, China, Tunisia, Argentina and Brazil had earlier qualified alongside hosts Great Britain.

Former Utah Jazz forward Andrei Kirilenko led the Russians with 19 points and eight rebounds as the 2007 European champions opened up a massive 20-point lead in the third quarter.

Stubborn Nigeria, who had stunned Greece to reach the last four, refused to lie down and cut the deficit to 73-67 before Kirilenko and the game's top scorer Alexey Shved, who had 22 points and six assists, stepped up and sealed Russia's win.

"We worked very hard over the last two months and earned our spot in the Olympics," an overjoyed Kirilenko told the world basketball governing body's (FIBA) television.

"Credit to the Nigerians, they are a very good team and made it difficult for us and we know that every team in the Olympics will be tough to beat," he said.

Lithuania, who won the 2003 European Championship but underperformed in last year's event on home soil, brushed aside the Dominicans with five players in double scoring digits.

Jonas Maciulis led the way with 19 and Jonas Valanciunas added 17 as the Lithuanians nailed nine of 13 shots from the field in the second quarter to take a 16-point halftime lead.

"We are happy to have qualified for the Olympics, my second, it was a really tough tournament but once again we proved that we are a strong basketball nation," said Maciulis.

"Now we have to prepare to be at our best in the Games and we are looking forward to the challenge."

(Writing by Zoran Milosavljevic in Belgrade; Editing by Amlan Chakraborty)