UNITED NATIONS (CNN) -- U.N. peacekeepers in Liberia now have the authority to arrest former President Charles Taylor and transfer him to Sierra Leone for trial should he return to the country.The U.N. Security Council on Friday voted unanimously to expand the mandate of the peacekeepers on the heels of Tuesday's democratic presidential elections in Liberia. With nearly all the votes counted, Ellen Johnson-Sirleaf was poised to defeat international soccer star George Weah in a runoff. Johnson-Sirleaf would be Africa's first democratically elected female president.Diplomats said they received reports Taylor had been active behind the scenes, trying to influence Liberia's elections. The current Security Council president, Russian Ambassdaor Andrey Denisov, said the resolution was intended to send a "strong signal" to Taylor that he would be expected to face trial.There was no agreement in the Security Council on a call to extradite Taylor from Nigeria, where he was given asylum in July 2003 as the United States and other nations sought to bring an end to years of civil war in Liberia.Nigeria -- the powerful nation that currently heads the African Union -- has resisted calls to hand over Taylor, citing its agreement with Taylor for asylum. Taylor's exit from Liberia was part of a peace deal.A diplomat from Denmark who co-sponsored the resolution called it "more preventive action, and now we'll have to work on how we get him extradited. ... At least now it tells Taylor to stay out of Liberia."Taylor -- Liberian president from 1997 until forced out in 2003 -- was indicted in 2003 by a U.N.-backed court in neighboring Sierra Leone. The charges of war crimes were related to his support for rebels in Sierra Leone who were committing widespread atrocities against civilians. He reportedly supplied arms to the Sierra Leone rebels in exchange for diamonds.Taylor also is banned from traveling outside Nigeria under a previous U.N. resolution. A U.N. panel of experts has said he has violated this ban within Africa.There are roughly 15,000 U.N. peacekeepers in Liberia. After a briefing by top peacekeeping official H�di Annabi, the Security Council "welcomed the peaceful and orderly conduct of the elections," Denisov said in a written statement.The council, he said, "underlined that the completion of free and fair presidential elections will be a key step forward towards restoring the normal state functions of Liberia and will pave the way for the return of Liberian refugees."But Weah, who came out ahead in the first round of voting, has alleged fraud in the runoff. His supporters have taken to the streets, clashing with peacekeepers and police even as the candidate appealed for peace. Johnson-Sirleaf, a Harvard-educated economist and political veteran, said she will offer her opponent a job, possibly the ministry of youth and sports. "I hope he will agree to work with me," she said.Denisov's statement said the council "urged the candidates, their parties and all their supporters to respect the final results of the election once they are officially declared."Liz Neisloss and Zain Verjee contributed to this report.