Liberia's president has warned its former rebel fighters not to get involved in the Ivory Coast crisis.
Both Laurent Gbagbo and Alassane Ouattara claim to have won last month's poll, raising fears of renewed conflict in the world's largest cocoa producer.
Neighbours Liberia and Ivory Coast have previously been involved in each other's conflicts.
The UN, US and African leaders say Mr Ouattara won and have urged Mr Gbagbo to step down.
Ivory Coast has been suspended from the West African regional bloc Ecowas until Mr Gbagbo cedes power.
But the US says Russia is blocking a UN Security Council statement endorsing Mr Ouattara as president.
Both men were sworn in as president last Saturday.
The rebel New Forces, whose leader is Mr Ouattara's prime minister, continues to hold northern Ivory Coast, while government forces are loyal to Mr Gbagbo.'Unscrupulous people'
Liberian Information Minister Cletus Seah told the BBC that President Ellen Johnson-Sirleaf had given a stern warning to former Liberian warlords not to get involved in the Ivory Coast situation.
"Some of these people have been contacted, according to our intelligence, by people we will describe as 'unscrupulous people' who want to cause some problems in the Ivory Coast," he said.
Mr Seah said it was not clear which side the warlords were being asked to back.
Liberian fighters were involved in Ivory Coast's 2002 civil war, which left the country divided, while Charles Taylor launched his Liberian rebellion from Ivory Coast in 1989, sparking 14 years of bloodshed.
Liberia is now slowly rebuilding after the end of its conflict.
In Abidjan, Mr Gbagbo and Mr Ouattara have both appointed cabinets.
Mr Ouattara is operating from a luxury hotel, guarded by UN peacekeepers.
The US says the UN mission in Ivory Coast is empowered to certify the election results and says Mr Ouattara won.
Us ambassador to the UN Susan Rice argued that failing to join international calls to respect the results risked exposing the Security Council as impotent.
"This is an important moment for the Security Council. The results are known, the facts are clear, and they need to be acknowledged and respected, that's the position of the United States," she said.
Earlier in the day the UN representative in Ivory Coast told the council that he had double-checked the results and was certain that Mr Ouattara had won by a clear margin.
Speaking via video link from Abidjan, Choi Young-jin urged the council to take action against Mr Gbagbo to safeguard the result of the vote.
Ms Rice said she hoped the Security Council debate could resume on Wednesday.
Russia says the UN would be exceeding its mandate if it declared the winner of an election.
Correspondents say it is unclear what the international community can do if Mr Gbagbo refuses to step down.
The UN has some 8,000 peacekeepers in Ivory Coast.