Hungary's rightist Prime Minister Viktor Orban's far-right Fidesz party has swept the European Parliament election on Sunday, according to a telephone survey.

The survey, carried out by the Nezopont institute after polling ended at 7 pm (1700 GMT) forecasts Fidesz winning 56 per cent of the votes.

Two leftists parties, MSZP and DK, were projected to win 10 per cent each, the institute, which is close to Orban's government, said.

Hungarian election authorities will not release any data until voting ends in Italy at 11 pm (2100 GMT), but they did say the turnout was a new record for European elections in the country, reaching 42 per cent before the voting ended.

In 2014, Fidesz won 51 per cent of the votes cast and claimed 12 of the 21 Hungarian seats in the European Parliament.