The agreement for a "period of silence" came at the request of opposition leader Vitali Klitschko, who said he would update protesters at 8 p.m. local time about the progress of the negotiations, Interfax-Ukraine reported.
Yanukovych asked the speaker of parliament Thursday to call an emergency session of the Legislature, saying "the present situation requires immediate settlement," a live blog on Kyiv Post reported.
On Wednesday, Klitschko said anti-government protesters "will go on the attack" Thursday if Yanukovych slights or spurns their demands, an opposition leader said.
Klitschko spoke after emerging Wednesday from the opposition's first direct negotiations with Yanukovych that he said led to no concessions and almost a brush-off.
He said Yanukovych could end the standoff "without bloodshed" by calling early elections.
Prime Minister Mykola Azarov, who denounced protesters as "terrorists," said Wednesday opposition leaders should be "more humble" and not build threats into their demands.
"The opposition leaders should move away from the language of ultimatums," Azarov said.
"We are ready to compromise, to agree. The opposition leaders should understand that they also bear responsibility in avoiding a civil war, and bloodshed, and so does the government," he said.
At least five protesters were killed Wednesday in the first deaths in violence with police, the opposition movement's medical service told Ukraine's pro-opposition Hromadske Radio. About 300 people were wounded, medical coordinator Oleg Musiy said.
Four of the five people found dead had gunshot wounds to the head, independent online newspaper Ukrainska Pravda reported.
The government confirmed two deaths and said police were not responsible.
About 1,400 people required medical attention between Sunday and Tuesday, the movement said.
Opposition leader Arseniy Yatseniuk, head of the All-Ukrainian Union "Fatherland" party of jailed former Prime Minister Yulia Tymoshenko, told the rally opposition demands included lifting new anti-protest laws that went into effect Wednesday.
"If this does not happen, we will march forward together. If it's a bullet to the head, then it's a bullet to the head," he told the rally in remarks quoted by the BBC.
A wall of flames from a long row of burning tires leaped high into the air before dawn Thursday, live video streamed by Ukraine's Espreso.TV indicated.
Men stoked the fire with additional tires, decreasing the visibility of a phalanx of riot police, while authorities tried to douse the flames with fire hoses.
"Murderers!" the crowd quoted by the Kiev Post yelled at police.
Hundreds of protesters, including many women, stood under security-force spotlights, keeping up a steady beat on oil drums, iron plates and metal sheets, while men occasionally threw cobblestones at police displaying riot shields about 20 yards away, the live video monitored by United Press International indicated.
U.S. State Department spokeswoman Marie Harf condemned the growing violence.
"Increased tensions in Ukraine are a direct consequence of the Ukrainian government's failure to engage in real dialogue and the passage of anti-democratic legislation," she said.
The protests started in late November when Yanukovych broke a promise to sign political and free-trade agreements with the European Union and instead negotiated a multibillion-dollar financial aid package from Russia.
The protesters demanded he and his government resign and new elections be held.
Yanukovych has been president since February 2010.
The protests became violent Sunday after protesters, frustrated by what they saw as opposition leaders' passive speeches at an Independence Square rally, attacked police defending a road near the Parliament and other government buildings.
The EU said it would "rethink" its relationship with Ukraine "if there is a systematic violation of human rights, including shooting at peaceful demonstrators or serious attacks to the basic freedoms."
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