Ukrainian President Viktor Yanukovych said Friday he would call early presidential elections in a bid to put an end to bloody street battles that have left at least 80 people dead this week in Kiev.

The head of state also pledged to revert to the previous 2004 constitution, which gave the president fewer powers, and said he would start the process of forming a coalition government, according to a statement published on his Web site.

"In these tragic days, when Ukraine suffered such heavy losses, when people died on both sides of the conflict, I consider it my duty to the bright memory of the deceased to declare that there is nothing more important than human life," the president's statement read.

"There are no steps that we must not do together to restore peace in Ukraine," he added.

He did not provide timetables for the constitutional changes and early elections, although some media outlets said the new charter would take effect in 48 hours.

Media reports indicated the country's next presidential ballot would be held at the end of this year and not in 2015, as originally scheduled.

Prior to Friday's statement, the Ukrainian presidency announced that a tentative agreement had been reached in EU-brokered talks between government and opposition leaders to bring an end to Ukraine's political crisis.

Urgent round-the-clock negotiations mediated by European foreign ministers were held after dozens of people - including both pro-Europe demonstrators and police - were killed on Thursday, many of whom died of gunshot wounds.

EU mediators said protest leaders had agreed to sign the deal reached in the all-night talks.

Disturbances in Kiev since Tuesday have left 80 people dead, according to the latest official figures, although opposition groups say that nearly 100 people were killed on Thursday alone, when a truce agreed the previous night was shattered by clashes in the capital's downtown Independence Square.

The fatalities include 13 police officers, according to the Interior Ministry, which said another 67 cops had been taken hostage by protesters.

With police facing gunfire, Ukraine's acting interior minister said he authorized the issuance of military arms to his officers.

Hundreds of opposition protesters forced the riot police who had surrounded Independence Square to retreat on Thursday morning.

The protesters, wearing helmets and carrying shields, sticks and Molotov cocktails, took control of a section of Grushevski street, where the seat of the government is located.

Ukraine's crisis erupted at the end of November, when Yanukovych backed away from plans to ink a pact with the European Union and instead signed a $15 billion financial-aid package with Moscow.

Protesters took to the streets of Kiev and began occupying administrative buildings, prompting Ukraine's Parliament, controlled by Yanukovych's allies, to pass a package of laws on Jan. 16 restricting freedom of assembly, freedom of speech and other basic rights.

Violent clashes pitting demonstrators and riot police broke out three days later and left six dead and hundreds wounded.

Ukrainian officials and opposition leaders began seeking a negotiated solution to the crisis in the wake of the bloodshed.

The talks led to the resignation of Prime Minister Mykola Azarov and the repeal of the controversial anti-protest laws, but opposition demonstrators continued to demand that Yanukovych also step down. EFE