WASHINGTON (REUTERS) - The United States (US) on Saturday welcomed the release from prison of former Ukrainian Prime Minister Yulia Tymoshenko and pledged to work with its allies, Russia and international organisations to support a unified and democratic Ukraine.

"We have consistently advocated a de-escalation of violence, constitutional change, a coalition government, and early elections, and today's developments could move us closer to that goal," the White House said in a statement.

The White House praised the "constructive work" in Ukraine's parliament, which declared President Viktor Yanukovich constitutionally unable to carry out his duties and set an early election for May 25 after the pro-Russian president's violent suppression of demonstrations in Kiev.

Yanukovich abandoned the capital and said the parliament's actions amounted to an illegal "coup d'etat." The White House urged an end to violence by all sides and wished Tymoshenko a speedy recovery as she seeks appropriate medical treatment.

The apparent toppling of the pro-Russian Yanukovich came after violence that killed 77 in Kiev and transformed the centre of the capital into an inferno.