By Pavel Polityuk and Natalia Zinets
KIEV (Reuters) - Ukraine's biggest political party said on Tuesday it will rate the performance of Prime Minister Arseny Yatseniuk's government as "unsatisfactory" in an imminent vote that could precipitate a collapse of the coalition government and snap elections.
Parliament could vote as early as Tuesday on a report that reviews the government's performance in 2015 and its agenda for this year. The final time and day of the vote has not been confirmed.
If the government loses, lawmakers need 150 signatures in parliament to hold a no confidence vote, which could lead to national elections if the coalition cannot agree on a new cabinet. Two legislators told Reuters they had already secured the signatures.
Yuriy Lutsenko, the parliamentary leader of President Petro Poroshenko's party, said his party had "taken the decision to rate the cabinet ministers' work as unsatisfactory".
Poroshenko heads Ukraine's largest party, and Yatseniuk the next largest. Both are in the ruling coalition.
Maksym Burbak, the parliamentary leader of Yatseniuk's party, told lawmakers that the consequences of voting against the government would be felt "literally the next day - since this could trigger early elections and chaos."
The government's collapse would dismay Ukraine's international backers, who have invested much cash and political capital supporting the Ukrainian government in its standoff with Moscow after Russia's annexation of Crimea in 2014.
Ukraine's failure to tackle corruption and implement reforms has already derailed a Western aid program that keeps its war-ravaged economy afloat.
Last year, the International Monetary Fund gave Ukraine a $17.5 billion package to be spread over four years, but so far only $6.7 billion has been disbursed.
Ukraine has been waiting since October for the next tranche of aid, worth $1.7 billion, which has been held up by concerns over the slow pace of reform.
The economy minister quit at the start of February, complaining corrupt vested interests were meddling in his ministry's work.
Ukraine's hryvnia currency fell to a new 11-month low of below 27 to the dollar on Tuesday, central bank data showed, and has fallen 12.2 percent since the start of the year.
The government is struggling to haul Ukraine out of recession at the same time it is fighting a pro-Russian separatist insurgency in its industrial east.
Prime Minister Yatseniuk's approval ratings have plunged to less than 1 percent since taking office in 2014. He has no obvious successor, although the parliament speaker and the technocrat finance minister are considered contenders.
(Writing by Matthias Williams; editing by Alessandra Prentice and Katharine houreld)