KIEV, Feb. 21 -- A peace deal emerged Friday after talks between Ukrainian President Viktor Yanukovych and his pro- European opponents, pointing to a tantalizing sign of an end to the country's months-long tumultuous unrest triggered by Yanukovych's move to backtrack a trade and economic agreement with the European Union and turn to Russia for financial aid instead.

The deal, mediated by foreign ministers of Germany, Poland and France, envisages constitutional changes to reduce the president's power, formation of a national unity government within ten days and an early presidential election this year.

The package of measures, widely seen as concessions made by Yanukovych to his pro-European opponents to end the bloodshed, has scored a victory for the West in its geopolitical tug-of-war with Russia.

Sitting at the strategically important juncture between Russia and Europe, Ukraine has long been divided under competing influences from both powers for geopolitical interests. The recent bloody showdown between riot police and anti-government protesters starting Tuesday has further polarized the East European country.

If implemented, the peace deal is likely to end the protracted crisis in the country, and also represents a major setback for Moscow in its rivalry with the Europe for influence.

It remained unclear, however, whether all sides, including anti- government protesters demanding the ouster of Yanukovych, would buy the EU-brokered deal. Till now, protesters who have occupied a Kiev central square for nearly three months have shown little sign to move out.

Meanwhile, a Russia mediator confirmed Friday that Moscow did not signed the deal on the grounds that certain questions regarding the agreement remained unanswered.

Admitting that the talks to resolve Ukraine's crisis had produced progress, Vladimir Lukin, the Russian mediator sent to Kiev by President Vladimir Putin Thursday night, said that "there was no clarity about the parties to the talks and who will be responsible for which things."

At Ukraine's request, Putin decided late Thursday to send Lukin to Kiev for the marathon talks, which had already started with the participation of European Union (EU) mediators early in the day.

"It is a mistake for Russia to join Ukrainian authorities, the opposition and EU representatives in the negotiation so late," Rukin told local media. "One should have agreed on the format of the talks right from the start."

He stressed that the issue of talks between confronting sides was Kiev's domestic affair, and that Russia was just a "witness," alluding to strong EU sway during the talks.

DIMINISHED CLOUT OF YANUKOVYCH

The accord signed Friday stipulates that presidential elections will be held no later than December, instead of March 2015 as scheduled.

Within hours of the deal signing, Ukrainian parliament voted to revert to a 2004 constitution that sharply limits the power of the president and gives parliament greater control over the make-up of the government, including the prime minister.

The lawmakers also voted to sack Interior Minister Vitaly Zakharchenko who was blamed for this week's bloodshed.

In a further sign of Yanukovych's diminished clout, the Ukrainian parliament passed a bill that would allow the release of his arch-rival, former prime minister Yulia Tymoshenko, which was used to be a key condition for Kiev to sign the trade pact with the EU.

Tymoshenko, a key opposition leader, was convicted in October 2011 for abuse of power over a 2009 gas deal with Russia. She was also charged with embezzling an estimated 405 million U.S. dollars and evading taxes worth more than 87,000 dollars in the 1990s.

The 53-year-old opposition leader, who is now receiving medical treatment in a state hospital in eastern Ukraine, has denied all charges, saying they were politically motivated.

Ukraine's anti-government rallies, which started in November, turned violent Tuesday, when protesters attacked police with Molotov cocktails and set fires outside the parliament, while the police responded with stun grenades and water cannons. The standoff left at least 77 people dead and hundreds of other injured.