STOCKHOLM (AP):

Sweden has become the latest European country to have its political order shaken by a backlash against large-scale immigration, with voters giving a boost to a far-right party and weakening the more established ones.

Sunday's election left the two rival blocs - a centre-left group and a centre-right alliance - with roughly 40 per cent of the vote each, portending what is likely to be weeks of uncertainty and complex coalition talks before a new government can be formed.

The Sweden Democrats, which has roots in a neo-Nazi movement but has worked to soften its image, won 17.6 per cent, up from 13 per cent in 2014, for a third-place finish. That showing is not strong enough for it to lead a government, but it reflects how deeply Sweden, famous for its progressive policies, is being transformed by migration.

The country that is home to the Nobel prizes and militarily neutral policies for the better part of two centuries has been known for its comparatively open doors to migrants and refugees.

Sunday's general election was the first since Sweden, with a population of 10 million, took in a record 163,000 migrants in 2015 - the highest per capita of any European country.

That had followed the earlier arrival of hundreds of thousands of asylum seekers.

Since 2015, the centre-left government has sharply restricted immigration, but many Swedes complain that the society cannot cope with integrating so many newcomers, many of them Muslims from Africa and the Middle East.

The growing strength of the Sweden Democrats also reflects how old taboos are collapsing.

Only a few years ago, Swedes would be shunned as racist for suggesting that the country had limits on how many migrants it should take or for expressing the view that it was hard to integrate Africans and Arabs. But people, increasingly, are expressing such ideas more freely - adding to the support for the party.

While the result is a boost for the Sweden Democrats, the party fell short of pre-election predictions.

The Expressen tabloid said in an editorial that "it all pointed at the Sweden Democrats taking over the position as Sweden's second-biggest party. But the expected ... bang didn't happen."