Georgia’s increasingly authoritarian ruling party has claimed victory after preliminary results gave it a clear lead in a pivotal election focused on the country’s future path in Europe.

The Georgian Dream party of billionaire businessman Bidzina Ivanishvili is on 54%, based on more than 99% districts counted, the central election commission says.

The initial results were dramatically different from exit polls conducted by Western pollsters and the head of one of the opposition parties said they believed the vote had been “stolen from the Georgian people”.

“We do not accept the results of these falsified elections,” said Tina Bokuchava, head of the United National Movement.

Another opposition leader, Nika Gvaramia, said Georgian Dream had mounted a “constitutional coup”.

Both Georgian Dream and the four pro-EU opposition groups trying to end its 12 years in power had earlier claimed victory based on competing exit polls.

Voters turned out in big numbers on Saturday in this South Caucasus state bordering Russia, and there were numerous reports of vote violations and violence outside polling stations.

One opposition official in a town south of the capital Tbilisi told the BBC that he was beaten up first by a local Georgian Dream councillor, and then “another 10 men came and I didn’t know what was happening to me”.

A coalition of 2,000 election observers called My Vote said given the scale of vote-fraud and violence it did not believe the preliminary results “reflect the will of Georgian citizens”.

The opposition has described this high-stakes vote as a choice between Europe or Russia. Many saw the vote as the most crucial since Georgians backed independence from the Soviet Union in 1991.

As soon as voting ended, two exit polls by Edison and HarrisX for pro-opposition TV channels gave Georgian Dream 40.9% and 42% of the vote, with the total for the combined four opposition groups put at 51.9% and 48%. But a poll for the big, government-supporting Imedi TV channel gave Georgian Dream 56%.

Some time later, the central election commission (CEC) came out with initial preliminary results.

The commission had said that 90% of the vote would be released within two hours of the polls closing enabled by new electronic vote-counting system, and it was only on Sunday morning the preliminary results were almost complete.

The CEC has come under criticism for being too close to the government and for rushing through electoral reform ahead of the election without sufficient consultation.

“The onus is on a government body to provide transparency required in an electoral process,” said Dritan Nesho of HarrisX.

“We analysed the data from these precincts and there’s a wide discrepancy from the data we have. In some cases they have districts in Tbilisi where Georgian Dream are winning by 45% of the vote, whereas we know most of the opposition vote came from Tbilisi.”

Georgian Dream has already claimed an outright majority in parliament, as the combined four opposition blocs can only muster about 37% between them, according to the contested preliminary results.

Under Georgia’s new system of proportional representation, whoever wins half the vote wins half of the 150 seats. None of the other parties fighting the election reached the 5% threshold to get into parliament.

Bidzina Ivanishvili, who made his fortune in Russia in the 1990s, told supporters it was a “rare occasion in the world for the same party to achieve such success in such a difficult situation”.

However, opposition leaders and supporters had a very different take.

Tina Bokuchava said her party would not accept Georgia’s European future being stolen and she hoped the other main opposition groups would be able to agree on their next steps.

“This is the moment. In future there may be no such moment,” opposition voter Levan Benidze, 36, told the BBC. “I know there are a lot of geopolitical risks – from Russia – but this could be the pivotal moment, a turning point.”

Although Georgia was made a candidate to join the European Union last December, that move has since been frozen by the EU because of “democratic backsliding – in particular a Russian-style “foreign influence” law targeting groups receiving Western funding.

The USSR may have ceased to exist more than three decades ago, but Moscow still considers much of the old Soviet empire its own backyard and Russia’s sphere of influence.

It will have appreciated Georgian Dream’s campaign promise of a “pragmatic” Russia policy, not to mention Brussels’ decision earlier this year to halt Georgia’s EU accession process.

Georgian Dream has promised voters they are still on course to join the EU, but it has also accused the opposition of helping the West to open a new front in Russia’s war in Ukraine.

Georgia’s Russian neighbour still occupies 20% of its territory after a five-day war in 2008.

Bidzina Ivanishvili’s rhetoric has become increasingly anti-Western, indicating that a fourth term for Georgian Dream might pull the country back into Russia’s orbit.

Georgians had a simple choice, the party’s founder said after voting in Tbilisi: either a government that served them, or an opposition of “foreign agents, who will carry out only the orders of a foreign country”.

He has repeatedly spoken of a “global war party” pushing the opposition towards joining the war in Ukraine, with Georgian Dream (GD) cast as the party of peace. For many voters the message has worked.

“The most important thing – for me, my family, my grandchildren – is peace that I wish for all Georgians,” GD voter Tinatin Gvelesiani, 55, told the BBC at a polling station in Kojori, south-west of the capital. “Only Georgian Dream” would bring peace, she added.

Election observers reported a string of violations across the country, from ballot stuffing inside polling stations to intimidation of voters outside.

With less than an hour to go before the polls closed, pro-Western President Salome Zourabichvili appealed to opposition voters not to be intimidated.

“Don’t get scared. All this is just psychological pressure on you,” she said in a live address on social media.

The intimidation turned into violence for Azat Karimov, 35, the local chair of the biggest opposition party United National Movement in Marneuli south of Tbilisi.

He told the BBC how he was set upon when his team tried to investigate votes being falsified by Georgian Dream officials. He also alleged that voters were being bribed to back the governing party.

“[A Georgian Dream councillor]came with 10-20 people… before police could come I told him to calm down. Right away the councillor started beating me.”

On the eve of the vote, a Georgian monitoring group highlighted a Russian disinformation campaign aimed at the election.

The Kremlin has denied meddling in Georgia’s domestic affairs and alleged instead that the West had made “unprecedented attempts” at interference.

Earlier this year Sergei Naryshkin, director of Russia’s Foreign Intelligence Service, the SVR, accused the United States of planning a “Colour Revolution” in Georgia.