Oppositions lawmakers released tear gas in Kosovo's parliament on Friday trying to prevent the election of a new president, while crowds of anti-government protesters rallied outside the building.

Foreign minister and former premier Hashim Thaci is the frontrunner to become Kosovo's head of state, who is chosen by parliament. But the united opposition bloc and its supporters vowed to scupper Friday's vote with their protests inside and outside the legislature in the capital Pristina.

Hundreds of demonstrators rallied in Kosovo's capital on Wednesday, vowing to stay put until the government resigns, after spending a rainy night camped out at the protest site.

Opposition politicians, who are angry over an EU-backed deal with Serbia, launched the protest calling for snap elections outside the main government building on Tuesday.

Kosovo's opposition released tear gas in parliament for a sixth time Monday, despite a recent reprimand from the U.S. secretary of state over the ongoing disruption.

Opposition MPs have for more than two months paralysed the work of parliament in protest against EU-brokered dialogue and deals reached with Serbia, the country from which Kosovo declared independence in 2008.

Kosovo's opposition fired tear gas and pepper spray in parliament Tuesday while protesters outside threw stones and paint, in the latest eruption of a long-running protest against agreements made with Serbia.

Opposition MPs have been paralyzing parliamentary sessions for weeks in a bid to thwart EU-brokered dialogue and agreements with Serbia, the country from which Kosovo broke away and declared independence in 2008.

Kosovo's constitutional court on Tuesday suspended the implementation of a key EU-backed agreement with Serbia, after weeks of opposition protests against the deal.

The move came a day after the U.N. cultural body UNESCO rejected Kosovo as a member, in a vote hailed as a victory by Belgrade.

Opposition MPs in Kosovo on Thursday disrupted a parliamentary session by releasing tear gas into the chamber for the second week running, in protest at agreements made with Serbia.

Despite tight security at the entrance to prevent a repeat of last week's chaotic scenes, the deputies managed to sneak canisters into the parliament and open them before proceedings began, said an Agence France Presse journalist at the scene.

Opposition lawmakers released clouds of tear gas in Kosovo's parliament Thursday, causing two MPs to faint, in protest at a recent EU-brokered deal reached by the government with Serbia.

The session was immediately canceled as smoke filled the chamber and two female lawmakers were taken by ambulance to hospital, said an AFP reporter at the scene.

Kosovo opposition lawmakers on Tuesday pelted the prime minister with eggs, preventing him from addressing parliament over the ongoing dialogue with Serbia.

Isa Mustafa could not even begun speaking when opposition deputies started hurling eggs from their benches, prompting his bodyguards to rush to open umbrellas in a bid to protect him.

Serbia and Kosovo voiced satisfaction Wednesday with an EU-brokered deal on several key areas that represents a major step forward in normalizing ties between the former foes.

"We have gained more than we hoped for," Serbian Prime Minister Aleksandar Vucic told national broadcaster RTS of Tuesday's agreement.

Five people suspected of planning a "terrorist attack" aimed at contaminating the water supply in the Kosovo capital Pristina have been arrested, officials in the breakaway Serbian territory said Sunday.

They are appearing before an investigating magistrate in Pristina, court president Hamdi Ibrahimi told reporters.