Foreign Secretary William Hague said he was in close touch with European Union partners over what he called the "extraordinary developments" in Ukraine.
"Events in the last 24 hours show the will of Ukrainians to move towards a different future, and ensure that the voices of those who have protested courageously over several months are heard," Hague said in a statement.
"We will work closely with our EU partners in support of a new government in Ukraine, as and when that is formed.
He said the release of jailed pro-Western opposition icon Yulia Tymoshenko was welcome.
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In a tweet, Hague said he had agreed with his German counterpart Frank-Walter Steinmeier to push for a "vital" International Monetary Fund financial package for debt-laden Ukraine.
A Foreign Office spokeswoman said: "One of the things they talked about was the economic situation and putting together a financial package which will help to stabilise the situation in Ukraine, to enable the Ukraine to receive long-term support from the IMF."
Yanukovych's regime appeared close to collapse as protesters took control of his offices and lawmakers voted to free former premier Tymoshenko immediately.