HELSINKI -- An opposition party favoured by Latvia's large ethnic Russian minority has won the Baltic nation's parliamentary election, but it's expected to face difficulties forming a ruling coalition after a vote that saw new populist parties surge and government parties falter.

Voters in Latvia, a member of the European Union and NATO, chose Saturday from more than 1,400 candidates and 16 parties to fill the country's 100-seat parliament.

With all the votes counted, results Sunday from Latvia's electoral committee showed the left-wing Harmony party winning with 19.8 per cent support.

The country's Russian minority is a major political force as it accounts about 25 per cent of Latvia's nearly 2 million people, a legacy of nearly 50 years of Soviet occupation that ended in 1991.

Harmony is led by Nils Usakovs, the mayor of Riga, the capital, since 2009. But it has been shunned by other Latvian parties and kept out of the Cabinet over suspicions that it's too cozy with Moscow, despite the party's pro-EU stance.

Sunday's result would give the party 23 seats at the Saeima legislature, one less it has now.

Voters, however, dealt a severe blow to Latvia's current three-party ruling coalition led by Prime Minister Maris Kucinskis.

His centrist Union of Greens and Farmers came in sixth place with only 9.9 per cent support, while the government's junior partners -- the conservative National Alliance and the liberal New Unity -- were fifth and seventh with 11 per cent and 6.7 per cent of the vote.

Two new smaller parties running on a strong anti-establishment, anti-corruption agenda moved into the forefront of Latvia's complex political landscape.

The populist KPV party -- abbreviation for "Who Owns the State? -- led by the colorful actor-turned-lawmaker Artuss Kaimins and the anti-corruption New Conservative Party took second and third place, with 14.3 per cent and 13.6 per cent of the votes respectively.

The liberal For Development/For! party also made a good run and got 12 per cent support.

A total of seven parties exceeded the five per cent threshold for getting seats in parliament.

Voter turnout was 54.6 per cent according to preliminary data, the lowest since Latvia regained independence in 1991, the Baltic News Service reported.

The result means difficult weeks ahead trying to form a broad government coalition that has at least 51 seats in parliament. Only KPV has so far indicated it is open for talks with Harmony, the possible kingmaker.

But Harmony's pro-Russian stance is still an issue.

Relations between Russia and Latvia have been frayed by Russia's 2014 annexation of the Crimea Peninsula from Ukraine and its support for separatists in eastern Ukraine.

Russian President Vladimir Putin has taken a strong interest in defending the rights of ethnic Russians in the Baltics, and the Baltic nations of Estonia, Latvia and Lithuania have been wary of increased Russian military presence in the region.

Earlier this year Harmony cut its co-operation deal with Putin's United Russia party - a pact that was a major source of irritation to other Latvian parties.