Swedish Prime Minister Fredrik Reinfeldt's center-right four-party coalition -- made up of the Moderates, the Liberals, the Christian Democrats and the Centre party -- held on to power, but lost its outright majority.

His coalition won 49.3 percent of the vote, officials at the Swedish Election Authority said after all 5,668 voting districts reported. The opposition "red-green" coalition -- consisting of the Social Democrats, the Left party and the Green Party -- had 43.7 percent of the vote, election officials said.

The far-right anti-immigration Sweden Democrats party also made a strong showing, winning 5.7 percent of the vote and a place in the national parliament for the first time. With possession of 20 seats, the party could wind up tipping the balance of power between the two major coalitions, although party leaders, including Reinfeldt, have vowed not to cooperate with the Sweden Democrats.

The leader of Sweden's red-green opposition coalition, Mona Sahlin, conceded defeat Sunday night. She told her supporters they were not able to regain the trust of the voters.

The ruling coalition won 172 seats, while Sahlin's group took 157 in the 349-seat parliament.