MONROVIA (AP) ― A group of Liberian opposition parties said Saturday they are pulling out of a recent presidential poll and threatened to refuse the results over allegations that election officials are skewing the outcome in favor of the president.

Saturday’s statement was signed by eight parties, including those of second-place challenger Winston Tubman and third-place contender Prince Johnson. The latest partial results gave President Ellen Johnson Sirleaf a narrow lead in the race.

In a statement, the group claimed “massive fraud being carried out by the National Elections Commission in the handling and reporting of the presidential election results in favor of President Ellen Johnson Sirleaf and the Unity Party.”

“We direct all our party agents assigned at (the electoral commission) in all capacities to withdraw effective immediately,” the statement read. “If the process continues we will not accept the results.”

The parties said they could offer photographs and witnesses to back their claims. They also called for a Sunday rally but did not specify a time or place.

International and local election observers said Tuesday’s election was peaceful, and there were no major breaches in voting and no serious incidences of violence.

Electoral commission spokesman Bobby Livingstone did not immediately address the allegations. “The commission is going to come up with a position on this later,” he said. “There may be some legal implications.”

Johnson and other politicians spoke after the statement was read. “It is a sad day for Liberia,” Johnson said. “In 1985 when Madame Sirleaf won a seat in the senate, she did not take it because she felt the election was rigged and that brought trouble to this country. Now, to see this strong woman who advocated for peace, justice, transparency and accountability to now be the one to rig elections through the election commission is sad thing indeed.”

Johnson, whose rebel army invaded Monrovia in 1990, videotaped himself ordering his men to cut off the ears of the country’s captured former president Samuel Doe, who later died.

Johnson has tried to refashion himself as a politician, and became a born-again Christian after the war, then went on to be elected senator of his home county.

On Saturday, he appealed to Liberians to remain calm.

“We want peace for Liberia,” he said. “We want stability. We call upon all Liberians to remain peaceful as we find peaceful solutions to this situation.”

Wilmot Paye, the secretary-general of the ruling Unity Party, said the party was not surprised by the allegations.

“What they have done today is something that we had anticipated,” he said. “They are doing this thing because it is not going their way. That’s why they want to create chaos.”

Also on Saturday, police said an office occupied by the ruling party burned down overnight. Police spokesman George Bardue said police were pursuing suspects but have made no arrests.

Counting is ongoing. Sirleaf led late Friday with 45.4 percent of the vote, falling short of the majority needed to avoid a runoff, according to partial results.

The Harvard-educated Sirleaf, who was Africa’s first democratically elected female president, faced 15 challengers. She is viewed abroad as a reformer and was awarded this year’s Nobel Peace Prize for her role in stabilizing Liberia after a 14-year civil war.

The results had been tallied from 2,242 polling stations representing more than half of the nation’s 4,457 voting centers. While Sirleaf led with 265,883 votes, the party of Tubman and soccer star George Weah trailed with 172,681 votes, or 29.5 percent. Johnson came in third in the race with 66,419 votes, or 11.4 percent, and said he is looking forward to playing the role of kingmaker.

This is not the first time challengers have claimed fraud in a Liberian election. After the country’s first postwar presidential poll in 2005, Weah ― who ran for president ― alleged massive fraud and contested the ballot. International observers said the vote was largely clean.

“We were given the right to exercise our civil liberty to go and vote, and our votes should be counted right,” Weah said Saturday. “Madame Sirleaf does not have to be president of this country if the people don’t want her to be. We are asking the international community to go back to the drawing board.”