Austria was shaken by a political earthquake yesterday when the neo-fascist right emerged from a general election as a contender to be the strongest political force in the country for the first time.

The combined forces of the extreme right took 29% of the vote, with Jörg Haider almost tripling the share of his breakaway Movement for Austria's Future to 11%, while his successor as Freedom party leader, Heinz-Christian Strache, saw his party soar to 18%.

The far right's vote doubled compared with the last election in 2006, putting it within less than a point of overtaking the poll victor, the social democrats.

The two big parties, which have run Austria since the second world war, slumped to their worst ever election toll. The Christian democrats (ÖVP), fared particularly poorly at around 26%, down 8%. The social democrats (SPÖ), under a new leader, Werner Faymann, took around 30% and laid claim to the chancellorship.

The early election was triggered by the collapse in June of the coalition of social and Christian democrats after only 18 months. The extreme-right profited from popular disillusion with the two big parties, which took months to form a "grand coalition" in 2006 and then spent the next 18 months paralysed by internal bickering. The same situation may repeat itself now, with both parties under different leaders and struggling to justify legitimacy.

Faymann, the likely new chancellor, is a 48-year-old from Vienna, who was supported by the main rightwing and fiercely anti-EU tabloid, Kronenzeitung, after he promised to put new EU treaties to a referendum in a country that matches Britain in Euro-scepticism.

The far-right triumph was greater than its breakthrough in 1999 when Haider's Freedom party came second in a general election with 27% of the vote and entered government, sparking a crisis that saw Austria isolated internationally.

Strache, who has been associated with neo-Nazi militants who deny the Holocaust, according to a court ruling, and who wants a new government ministry created to manage the deportation of immigrants, wound up his campaign at the weekend by calling Muslim women who wear the burqa "female ninjas".

He talked of east European immigrants to Vienna as "European brothers who don't want to be Islamised", while another of his party leaders reminisced about the days when the kiosks on Vienna's squares sold sausage and wiener schnitzel, rather than "the kebab joints selling falafel and couscous, or whatever you call that stuff".

Last night Strache said he should be the new chancellor. "Today, we are the winners of election night," he said.

The only realistic options for forming a viable grouping are for another grand coalition or for Faymann to contemplate a coalition with Strache, a Viennese former dental technician who has supplanted Haider as the national extreme-right leader. Senior social democrats said last night that they would not collaborate with the Freedom party. Any such move would trigger a deeper crisis within the SPÖ.

Despite mustering around 30% of the vote between them, Strache and Haider are sworn enemies and are unlikely to be able to work together. Both men are fierce critics of the EU.