Sweden's Prime Minister Ulf Kristersson has announced his resignation after losing the country's parliamentary election.

Centre-left opposition parties won 176 seats in Sunday's vote for parliament in Sunday's election while Kristersson's ruling right-wing bloc secured 173 seats, the election authority said earlier as the counting of ballots ended.

The election result sets the stage for Social Democratic party leader Magdalena Andersson to return as prime minister after four years in opposition.

All votes for the 349-seat parliament have now been counted, although the result remains subject to formal certification in the coming days.

Kristersson of the right-wing Moderates Party had previously commented publicly on the final result.