Far-right Hungarian party Jobbik has significantly increased its share of the vote in elections described by Jewish groups as “a dark day” for the country.

Having won more than one in five votes, the party with a history of anti-Semitic outbursts followed the election success of the French far-right party Front National last week, when Marine Le Pen won several towns and districts.

“This is truly a dark day for Hungary,” said Dr Moshe Kantor, president of the European Jewish Congress (EJC), who said Jobbik was “an unashamedly neo-Nazi political party” that “feeds on hate”.

He added: “These gains should serve as a wake-up call for Europe, where we are witnessing democracy being appropriated by the enemies of democracy.”

Jobbik remains the third largest political party in Hungary, after an election in which incumbent premier Victor Orban of Fidssz was re-elected.

In recent years it has sought to soften its image and distance itself from its more overtly anti-Semitic attitudes.

But Jewish groups point to several examples of concern, such as in November 2012, when Jobbik lawmaker Marton Gyongyosi said a census was needed of all Jews in Hungary, together with a list of Jewish lawmakers for “national security” reasons.

Critics say Jobbik is effective at using the consternation of others to generate free publicity, as at the party’s campaign launch on the site of a former synagogue, which had a plaque on the wall commemorating 500 Jews killed in the Holocaust.

Jobbik leader Gabor Vona hailed this weekend’s result, which surprised observers and saw his party’s share of the national vote jump from 15% to more than 21%.

Cas Mudde, an analyst at the University of Georgia, said Jobbik’s showing was the strongest of any European far-right party in recent years, with the exception of Switzerland’s People’s party which won 26% of the vote.

But Kantor urged the national authorities in Hungary to turn on Jobbik, saying: “The new Hungarian government must ensure now that this hate is not tolerated, not by the government, not in parliament and not on the streets of Hungary.”