Sweden faces political deadlock after gains by far-right party

The Sweden Democrats, a party with roots in the white supremacist fringe, won 17.6 percent and 63 seats, up from 12.9 percent and 49 seats in the last election four years ago, the biggest gain by any party in Sweden's parliament, the Riksdag.

The results were largely in line with the conventional opinion polls tracked by Reuters in the run-up to the election but well below some online surveys that had predicted the Sweden Democrats could become the largest party.

While the results also fell short of leader Jimmie Akesson's predictions of 20 percent of the vote or more, he told a party rally it was nevertheless the winner of the election.

"We will gain huge influence over what happens in Sweden during the coming weeks, months and years," Akesson told party colleagues.

Akesson hopes his party, which wants Sweden to leave the European Union and freeze immigration, can play a decisive role in negotiations over forming a government.

He called on Ulf Kristersson, the centre-right Alliance's candidate for the premiership, to choose between seeking support from the Sweden Democrats for an Alliance government or to accept another four years of Social Democrat Prime Minister Stefan Lofven.

Kristersson called on Lofven to resign, but rebuffed Akesson.

"We have been completely clear during the whole election. The Alliance will not govern or discuss how to form a government with the Sweden Democrats," he said.

The Sweden Democrats, shunned by all the other parties since entering parliament in 2010, have promised to sink any Cabinet that refuses to give them a say in policy, particularly on immigration.

Lofven said he would not resign and called for cross-party cooperation to resolve the political impasse.

"There is no side with a majority. Then it is only natural to work across the political divide to make it possible to govern Sweden," Lofven said.