British Prime Minister David Cameron says the deal agreed between Ukraine's embattled president and the opposition is a real chance to stop the "downward spiral into the nightmare" otherwise facing the country.
Cameron said the violence witnessed in Kiev this week, in which nearly 100 protesters have died, had "no place in 21st century Europe".
Ukrainian President Viktor Yanukovych has agreed to form a new unity government and hold early elections.
"I welcome today's agreement which offers a real chance to end the bloodshed and to stop the downward spiral into the nightmare that is facing Ukraine and her people," Cameron said in a statement.
"It should foster a lasting political solution to the crisis and President Yanukovych, his administration and the opposition must all get behind this deal and deliver it according to the timetable set out."
Cameron said he hoped the deal "will restore calm to the streets of Kiev and across the country".
"Such scenes of carnage are truly shocking and have no place in 21st century Europe."
Cameron has spoken to Russian President Vladimir Putin, German Chancellor Angela Merkel and Polish Prime Minister Donald Tusk in the last 24 hours.
"We all support this deal and want to see it work," Cameron said.
"And working with other European partners and the United States, we will do all we can to ensure it succeeds."
