Ukrainian opposition MPs succeeded in making sure an extraordinary session of parliament took place despite the earlier violence in Kyiv.
While they sang the national anthem, most governing party MPs stayed away.
A dozen did attend, agreeing to form an “anti-crisis group”.
Former boxing champion turned opposition leader Vitaly Klitschko said: “We have to make the police and the army pull back from the city centre in order to stop the violence. We have to start the process of coming back to the Constitution of 2004 as well. It’s very urgent. We have to force ministers to do their duty and not just protect their posts. It’s crucial in order to stop this bloodshed.”
There were scuffles when at least one government MP refused to back any opposition proposals.
The opposition want security forces pulled back from the conflict zone in Kyiv.
Their demand for a return to the previous constitution, ditched when Viktor Yanukovych took office, would reduce the president’s powers and increase those of parliament.
Diplomats said there were also indications that other members of the Party of Regions were distancing themselves from Yanukovych in the light of criticism from Moscow that he has not been decisive enough.
“There is indirect information that some of the Regions members of parliament are leaving the country or Kyiv,” said Volodymyr Fesenko, an analyst for Penta think-tank.