The bloc of political parties in Ukraine that supports pro-Western President Viktor Yushchenko has said it is leaving the governing coalition. The Our Ukraine bloc said it acted because the cabinet of PM Viktor Yanukovych was "wrecking" Ukraine's efforts to join the EU and Nato.
It said it would recall all its cabinet ministers and join the opposition.
Mr Yanukovych told Nato last month that Ukraine was not ready to join, defying Mr Yushchenko's position.
Mr Yushchenko was swept to power in 2005, following the so-called Orange Revolution - mass street protests against vote-rigging in the presidential elections in 2004.
However, internal squabbles in Mr Yushchenko's camp allowed Mr Yanukovych - widely seen as being backed by Russia - to stage a dramatic comeback in parliamentary elections in March this year.