Riga (AFP) - Latvia's ruling centre-right coalition led by Prime Minister Laimdota Straujuma scored a resounding majority in Saturday elections overshadowed by alarm over a resurgent Moscow and a Kremlin-allied party popular with the country's sizeable Russian minority.

An exit poll by the SKDS agency gave three parties in her coalition 63 seats in the 100-member parliament, while their Kremlin-allied leftist rival took 23.

"This is a vote of confidence in (Straujuma's) Unity party and in the coalition... it means people want us to continue our work," parliamentary speaker Solvita Aboltina and Unity party chair told Latvian public broadcaster LTV.

Unity scored 25 seats while its coalition partners National Alliance and the Greens and Farmers scored 19 seats each respectively, according to SKDS.

Nils Ushakovs, leader of the Kremlin-allied leftist opposition Harmony Party -- which exit polls showed came second with 23 seats -- called the result "positive" but told LTV "we shouldn't rely on exit polls."

"This is more of the same coalition, but it's slightly changed in the balance of power and that makes Unity more powerful," University of Latvia Professor Ivars Ijabs told AFP.

"The probability that we will see someone other than Straujuma as prime minister is quite high," he added.

It was not immediately clear whether President Andris Berzins would ask the 63-year-old Straujuma, a pragmatic technocrat, to form a fresh coalition government.

Analysts in Riga believe Berzins could tap her Unity party colleague, outgoing EU development commissioner Andris Piebalgs, for premier as Latvia is poised to take over the European Union's rotating six-month presidency in January.

- Geopolitical jitters -

Russia's annexation of Crimea and meddling in eastern Ukraine have sent shudders through this NATO and eurozone member of two million people where many retain vivid memories of the Soviet occupation that ended just a quarter-century ago.

With Europe now in its worst standoff with Russia since the Cold War, many Latvians fear Moscow could attempt to destabilise its Soviet-era Baltic backyard.

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Straujuma has called for more NATO troops and extra air patrols in the region and the alliance has responded with increased troop rotations and exercises.

Casting her ballot near Riga on Saturday, she slammed Ushakovs who recently said that given the choice of Russian politicians "the best thing possible right now is President Vladimir Putin".

"Security is crucial... I can't support the view that Putin is the best possible president for Russia," Straujuma said.

The Harmony Party is popular among ethnic Russians -- who make up a quarter of Latvia's population -- and actually topped the poll in 2011.

But it has always failed to find coalition partners among the ethnic Latvian parties and been relegated to the opposition.

"If Harmony ever got in, it would be a disaster for the country. They would sell it to Russia," Karlis Kalnins, a musician, told AFP in the capital Riga.

Pensioner Leonids, an ethnic Russian who declined to give his last name, told AFP at a Riga polling station that Harmony got his vote for their generous approach to social spending.

- Sanctions woes -

Concern is also running high over the impact that tit-for-tat sanctions between Moscow and Brussels over the Ukraine crisis could have on this tiny Baltic state, heavily reliant on trade with Russia.

Latvia made a spectacular recovery from the world's deepest recession in 2008-09, when output shrank by nearly a quarter during the global financial crisis.

A painful austerity drive by a centre-right government then paved the way for entry into the eurozone in January.

The sacrifices paid off and growth in Latvia topped the 28-member EU for a third consecutive year in 2013, with a 4.0 percent expansion.

Forecasts had pointed to nearly five percent growth this year, but the escalating sanctions war could hit Baltic trade, transit and tourism.

"I voted for Unity on the basis that they are the best among the bad options," Maris Skrastins, 25, told AFP in Riga. "I trust them with the economy more than the others."

Turnout stood at 57 percent, according to the state elections commission. Official results are expected Sunday afternoon