Officials in Georgia said a partial recount confirmed the ruling party had won its disputed election, with Washington and Brussels demanding an investigation.

However, the pro-western opposition said Saturday’s parliamentary vote had been “stolen” by the ruling Georgian Dream party and it refused to recognise the results, plunging the Caucasus country into uncertainty.

The pro-European president, Salome Zourabichvili, who is at loggerheads with the governing party, has declared the election results “illegitimate”, alleging there was a “Russian special operation” to undermine the vote –which the Kremlin has denied.

The central election commission told AFP on Thursday that a recount at about 12% of polling stations, involving 14% of the vote, “didn’t lead to a significant change to previously announced official results”.

“Final tallies only slightly changed at some 9% of recounted polling stations,” a spokesperson said.

Tens of thousands of people thronged the streets on Monday to protest against the alleged fraud.

International observers, the EU and the US have criticised electoral irregularities and demanded a full investigation. Georgia is an EU candidate.

Georgia’s interior ministry said two people had been arrested after alleged ballot stuffing at a provincial polling station, while prosecutors said they had opened 47 criminal cases over alleged electoral violations.

On Wednesday, Georgian prosecutors said they had summoned Zourabichvili for questioning, because she “is believed to possess evidence regarding possible falsification”. The figurehead president refused to comply, saying plenty of evidence of electoral fraud was available and prosecutors should focus on their investigation and “stop political score-settling with the president”.

Opposition parties said they would not enter the new “illegitimate” parliament, and demanded fresh elections.

The International Society for Fair Elections and Democracy, a Georgian NGO, said in a report released on Thursday that the results “regardless of the outcome, could not be seen as truly reflecting the preferences of Georgian voters”. The group said it had documented “serious (electoral) violations”, including “intimidation, ballot stuffing, multiple voting, unprecedented levels of voter bribery and expulsion of observers from polling stations”.

A group of Georgia’s leading election monitors said earlier that they had uncovered evidence of a complex scheme of large-scale electoral fraud that had swayed results in favour of the ruling party.

Before the elections, Brussels cautioned that they would be a crucial test for Tbilisi’s fledgling democracy and would determine its chances of joining the bloc.

The European Commission said in a report published on Wednesday it could not recommend opening membership talks “unless Georgia reverts the current course of action which jeopardises its EU path”.

Critics of the increasingly conservative Georgian Dream party accuse it of derailing efforts to join the EU and of bringing the former Soviet country back into the Kremlin’s orbit.

The EU halted Tbilisi’s accession process after Georgian Dream passed a law this year on “foreign influence” that opponents said mirrored repressive Russian legislation, and which has prompted weeks of large-scale street protests.

The prime minister, Irakli Kobakhidze, insisted the elections were “entirely fair, free, competitive and clean” and that EU integration was his government’s “top priority”.

Near-final election results showed Georgian Dream won 53.9% of the vote, compared with 37.7% for an opposition coalition.