Ukraine’s opposition demand changes to the constitution

Ukraine's opposition is to push for a vote in parliament on changes to the constitution - a move aimed at curbing President Viktor Yanukovych's powers.

The opposition has repeatedly warned that failure to act will further inflame mass anti-government protests.

A protest rally is also expected outside the parliament building in the capital Kiev.

Pro-presidential MPs - who have a majority - have opposed attempts to return to the 2004 constitution.

Ukraine's MPs are due to begin their parliamentary session at 10:00 local time (08:00 GMT)

The opposition has been pushing for weeks for a return to the 2004 constitution, which would mean President Yanukovych losing some of the powers he has gained since his election in 2010.

The changes would mean that parliament - not the president - would be appointing the prime minister and most cabinet members as well as regional governors.

The move could also lead to snap presidential elections - a key demand of the opposition.

MPs who support the president have argued that different proposals on how to return to the previous constitution legitimately have not been thoroughly discussed, and more time is needed to iron out all the differences between the two sides.

Meanwhile, anti-government protesters are planning to march on parliament to demand the constitutional changes be implemented.

The parliament and key government buildings have been guarded by riot police , and there are fears that clashes may erupt later on Tuesday.