Clashes between Bulgarian police and protesters left over 45 people injured on Wednesday as parliament met to start discussing a project for a new constitution aimed at quelling weeks of anti-government rallies.
Demonstrators have been blocking roads and staging daily protests in the capital Sofia and other cities for close to two months, pressing for the resignation of Prime Minister Boyko Borisov and chief prosecutor Ivan Geshev over their perceived links with behind-the-scenes oligarchs.
Borisov has already sacked several key ministers and recently proposed adopting a new constitution, but the protesters have dismissed these moves.
Thousands of demonstrators took to the streets of central Sofia from early Wednesday into the evening, shouting "Resign" and "Mafia".
At some points protesters threw paving stones, eggs, apples and tomatoes at police.
Officers moved to disperse the crowd with stun grenades, pepper spray and tear gas.
Hospital officials said over 45 people, including at least 27 policemen and several journalists, were injured during clashes as protesters tried to break the cordons of officers in full anti-riot gear encircling the parliament building.
Six were hospitalised for injuries including chemical burns and breathing problems.
Sofia city police chief Georgy Hadzhiev denied accusations by the Bulgarian Helsinki Committee rights NGO that the police had used disproportionate force.
- Confidence 'definitely lost' -
Hadzhiev said that over 35 people were arrested, most of them football ultras with previous criminal records.
The clashes came at the start of parliament's autumn session, which is expected to discuss a proposal for a new constitution that stands little chance of success.
On Wednesday Borisov's GERB party garnered the necessary support from over 120 lawmakers to put the project forward but it looks highly unlikely to gain the 160 votes which would be needed for it to progress to the next stage of adoption.
In a statement inside parliament, President Rumen Radev, who has voiced support for the protesters' demands, called on lawmakers to "emerge from the crisis with dignity" by paving the way for early elections.
"Confidence is definitely lost," he said.
Borisov, who has been in power almost without interruption for more than a decade, has so far refused to resign before his third term expires in March next year.
Analysts have dismissed the conservative premier's proposal for a new constitution as an attempt to win time and cling to office.
Activists too have slammed it for failing to improve the accountability of the chief prosecutor -- an issue long highlighted by Bulgarian and international observers as well as the European Court of Human Rights -- while trying to limit the rights of the president.
Thirteen years after joining the EU, Bulgaria remains its poorest and most graft-ridden member, according to Transparency International's corruption perceptions index.