HELSINKI (Reuters) - Finnish opposition parties demanded the government resign, saying on Monday its plan to stay in power after the break-up of one of its coalition partners was a cynical move that did not reflect the voters’ will.

The ruling center-right coalition was shaken last week after Prime Minister Juha Sipila ejected the nationalist Finns Party which had just chosen a new leader with hardline views on immigration.

Sipila initially said the government would fall - then said he had changed his mind after a more moderate faction in the Finns party broke away and said it could still work with the coalition.

Finland’s Aamulehti newspaper reported that the changes had been planned before the Finns Party chose a new leader, suggesting the process had been stage-managed - an accusation dismissed by the government.

“It was not a crisis but a carefully planned strategy. Can politics get any more cynical?” said Li Andersson, chairwoman of the opposition Left Alliance.

Antti Lindtman, a member of the opposition Social Democrats, said the government in its new form was weaker “both morally and in the parliament”.

“Resignation and new government formation talks would have offered a chance to search for alternatives,” he said.

The coalition - with Sipila’s Center Party, the pro-EU National Coalition Party (NCP) and the “New Alternative” faction from the Finns party, has 106 of the parliament’s 200 seats. The next elections are due in 2019.

Vesa Vares, a political scientist at the University of Turku, said the government should have at least met the opposition parties before announcing they were carrying on under the new arrangement.

Parliament will hold a vote of confidence on the reformed coalition on Tuesday.

Laura Huhtasaari, from the part of the Finns party now in opposition called Sipila’s move “an impudent act ... In Finland’s centenary year, we have a turn-coat government.”