Monrovia - One of Liberia's largest political parties called for a halt to counting of election results on Thursday, alleging voting irregularities and fraud, as the country awaited the announcement of the first provisional results.Angry supporters gathered to protest at Liberty Party headquarters, claiming polls in the West African nation opened late and that ballot-tampering occurred in at least one location in the capital, Monrovia."These people stood in the rain and under the sun; these people sacrificed," the party's vice chair for political affairs, Abe Darius Dillon, told The Associated Press. The Liberty Party's flag-bearer is Charles Brumskine, a corporate lawyer who placed third in 2005 elections and fourth in 2011.The National Election Commission has said it would start to release provisional results on Thursday evening. Liberians on Tuesday voted among 20 presidential candidates to succeed Nobel Prize winner Ellen Johnson Sirleaf, who led the country's recovery from civil war and a deadly Ebola outbreak. A runoff election is likely.The election commission is ready to listen to official complaints, but vote-counting will continue, spokesperson Henry Boyd Flomo said."The constitution mandated us to conduct elections and declare results therefore in 15 days," Flomo said. "We've got no option, but to live with that." He said he could not address the accusation of ballot-tampering, but acknowledged that many voters found it difficult to find their voting station. Everyone was allowed to vote, he added.A presidential candidate must win more than 50% of the vote to avoid a second round.The Carter Centre, which observed elections, commended Liberians "for the calm and peaceful atmosphere" of the vote. "No matter the outcome of this election, it will result in a transfer of power from one democratically elected government to another for the first time in the lives of many Liberians," it said in a statement.The Carter Centre noted difficulties with long lines and management of voter lists but said it could not give a final assessment until vote-counting is complete. It encouraged the prompt release of provisional results.