TBILISI, Georgia — Mikhail Saakashvili was narrowly re-elected as Georgia’s president, election officials said yesterday, announcing preliminary results that threatened to inflame tensions in this former Soviet republic but appeared to avoid a runoff for the pro-Western leader.

According to the tally based on results from nearly all precincts in Georgia, Saakashvili won 52.8%, compared to 27% for his main opponent, the head of the Central Election Commission, Levan Tarkhnishvili, said. His announcement took the country by surprise on the Orthodox Christmas Eve. Earlier yesterday, several thousand people rallied in Tbilisi, claiming the vote was rigged by the government of Mr. Saakashvili, who was once praised as an icon of democracy in the former Soviet Union but shocked his Western allies when he crushed anti-government demonstrations late last year and shut down an independent television station.

The influential election observer mission of the Organization for Security and Cooperation in Europe said the election revealed “significant challenges” but was generally in line with democratic commitments. The OSCE pointed especially to “an inequitable campaign environment” due to state activities overlapping Mr. Saakashvili’s campaign.

Opposition leaders said the campaign was unfair and alleged widespread voting violations. Addressing a crowd of some 5,000 people in a snowy square in Tbilisi, the opposition candidate, Levan Gachechiladze, said he came first in the vote and called for a second round. He cited a tally by his supporters who served on election commissions across the country.