The breakthrough agreement, aimed at ending the violence that has rocked the capital Kyiv over the past three days, was signed on Friday and will lead to elections by December 2014. Constitutional reform will start immediately in Ukraine, and must be completed by September.

Investigations into the violent scenes during several days of clashes between police and protesters in Kyiv's Independence Square - known also as Maidan - will also be conducted.

Lawmakers have wasted little time in voting through several significant motions. A return to the 2004 constitution, which moves significant powers from the president back to parliament, was first to be voted on. Decisions to grant amnesty to demonstrators arrested in the anti-government protests and the firing of interior minister Vitali Zakharchenko - followed. A vote to release Tymoshenko was then passed, with 310 lawmakers of around 380 in favor. It is as yet unclear, however, when she will be released from jail in Kharkiv.

The deal was brokered by Germany's Foreign Minister Frank-Walter Steinmeier and counterparts Radoslaw Sikorsi (Poland) and Laurent Fabius (France). It was signed by Yanukovych and opposition leaders Arseniy Yatsenyuk, Vitali Klitschko and Oleh Tyahnybok. Fabius described the negotiations that led to it as having been conducted in a "terrifying atmosphere."

"It's the exit from the crisis. In any case, everything is set up for that," he told reporters from Beijing, where he had travelled to from Kyiv on Friday.

'It's the beginning'

The deal has been widely welcomed, although Steinmeier spoke of the work still ahead. "This agreement is not the end of the process. It's the beginning of the process," he said.

White House spokesman Jay Carney called for immediate change: "Now the focus must be on implementing this agreement, which we will be monitoring closely," he said, adding the US would still impose sanctions on Ukraine if needed. United Nations Secretary-General Ban Ki-moon has urged Yanukovych to "implement the agreement fully as soon as possible," according to deputy spokesman Farhan Haq.

US President Barack Obama and Russian President Vladimir Putin spoke by phone late Friday evening. The conversation was "constructive," according to news agency Reuters, which cited a senior state department official. According to initial reports, Russia would be seeking a role in the implementation of the Ukrainian agreement.

The deal has not appeased all, however. Maidan is yet to clear of protesters, and opposition leaders have been booed during addresses. A speech by Klitschko was interrupted by an activist, who drew cheers when he warned protesters would not back down until Yanukovych was out of office. He pledged demonstrators would "attack with weapons" if Yanukovych was still president come 10 a.m. local time on Saturday.

Demonstrations over Yanukovych's decision to turn his back on a European Union association act in favor of closer ties with Russia had come to a head on Tuesday, with Ukraine's health ministry on Friday putting the death toll from clashes between protestsrs and police at 77. It added that 577 people had been wounded and 369 hospitalized.

ph/dr (AFP, AP, Reuters)