TBILISI — The head of Georgia's ruling party announced sweeping electoral reforms on Monday in a bid to appease protesters after days of demonstrations gripped the capital Tbilisi.

Speaking at a news conference following four days of protests, tycoon Bidzina Ivanishvili announced "large-scale political reform".

Parliamentary elections next year will now be held under a proportional voting system, he said, meeting a key demand of protesters who denounced the existing set-up as favoring Ivanishvili's Georgian Dream party.

"We will have a parliament where all the existing political actors will be represented," Ivanishvili said.

The protests, which erupted on Thursday, have seen thousands take to the streets of Tbilisi on consecutive nights and clashes with police firing tear gas and rubber bullets.

It was unclear whether the announcement would be enough to mollify protesters, who were also demanding a snap vote and the resignation of powerful Interior Minister Giorgi Gakharia.

On Monday afternoon, anti-government demonstrators drove dozens of cars around Tbilisi's central district, honking in protest before arriving at the interior ministry building to demand Gakharia's resignation.

Another mass street demonstration was planned for the evening.

Georgia's main opposition force, ex-president Mikheil Saakashvili's United National Movement (UNM), said that Ivanishvili's concessions were "only a partial victory."

The party would insist on holding early parliamentary polls after the electoral reforms are finalized, one of its leaders, Grigol Vashadze, told journalists.

Vashadze said mass rallies would continue until Gakharia resigns and the more than 100 protesters still behind bars — whom he referred to as "political prisoners" — are liberated.

The protests have sparked a political crisis and raised tensions with Moscow to levels not seen in years.

They erupted after a Russian lawmaker addressed parliament from the speaker's seat last week, a hugely provocative move for two countries whose ties remain strained after a brief war in 2008.

The rallies evolved into a broader movement against Ivanishvili, a billionaire businessman widely believed to be calling the shots in Georgia.

For days, protesters have gathered in front of the imposing building of Georgia's parliament, flooding the capital's main Rustavi Avenue and blocking traffic.

Placards have taken aim at Ivanishvili and Russian President Vladimir Putin who, in response to the protests, banned Russian airlines from flying to Georgia and Georgian carriers from traveling to Russia.

On Monday, Russian consumer watchdog Rospotrebnadzor said it had noticed a "deterioration" in the quality of Georgian wine and had "tightened control" of all Georgian alcoholic beverages entering Russia. Russia is a crucial market for Georgian wine exports.

The first day of the protests saw a violent police crackdown that left 160 demonstrators and 80 police officers injured. More than 300 people were arrested.

Media reports said several protesters — including a 19-year-old girl — lost their sight after being hit by rubber bullets.

Raising fears of the possible arrest of opposition leaders, Ivanishvili said on Monday that both those who provoked the violence and those who used excessive force "must be punished".

He has accused opposition leaders of inciting protesters to storm parliament — a claim they have denied.

Relations between Georgia and Soviet-era master Russia have long been fractured over Tbilisi's efforts to join the European Union and NATO.

The confrontation culminated in a war over Georgia's breakaway regions of Abkhazia and South Ossetia in August 2008.

After the conflict, which claimed the lives of hundreds of soldiers and civilians from both sides, Moscow recognized South Ossetia and another separatist enclave, Abkhazia, as independent states where it then stationed permanent military bases.

Tbilisi and its Western allies denounced the move as an "illegal military occupation" and insist it must end. — AFP