The Supreme Court of Liberia on Monday halted a presidential runoff election scheduled for Tuesday, delaying the first democratic transfer of power in the West African country in recent political history.

In a unanimous ruling, the court ordered the National Elections Commission to spend more time investigating a complaint from Charles Brumskine, the third-place finisher in the Oct. 10 election, that the vote had been marred by fraud.

The former soccer star George Weah and Vice President Joseph Boakai, the top two vote-getters in the election, were supposed to compete in the runoff, having finished with 38 percent and 29 percent of the vote. To win outright, a candidate needed more than 50 percent.

A number of international elections observers, including representatives of the Carter Center and the National Democratic Institute, said the Oct. 10 election was largely free and fair, despite a few irregularities at some polling stations.

Mr. Weah did far better than most political analysts had expected, and Mr. Brumskine, who finished in third place at 9.6 percent, was so far behind the top two that it was difficult to imagine how fraud could have significantly skewed the result, even if his complaints proved valid.

Elections commission officials had been investigating the fraud allegations, but had still planned to proceed with the scheduled runoff on Tuesday. The ruling by the Supreme Court stopped that plan.

As of late Monday, Mr. Weah’s political party, the Congress for Democratic Change, refrained from calling for supporters to protest the delay in the runoff. “We’ve been telling people to remain calm,” said Nathaniel McGill, the party chairman, in a telephone interview. “We will continue to ask our people to keep the peace because it’s important.”

He said that Mr. Weah was in Accra, Ghana, on Monday and would be traveling back to Liberia on Tuesday, at which point his party would issue an official response to the ruling.