Italy faces fresh political crisis as M5S threatens to shun vote of confidence.

The Italian government led by premier Mario Draghi risks collapse after the populist coalition partner MoVimento 5 Stelle (M5S) pledged to boycott a parliamentary confidence vote on Thursday.

M5S leader, former prime minister Giuseppe Conte, said on Wednesday night that his party would not back the vote on the €26 billion cost-of-living package in the senate.

Conte claims the government has not listened to M5S proposals including measures to tackle social problems. The party has also repeatedly voiced its opposition to Italy sending more military aid to Ukraine.

The M5S is willing to engage in dialogue and make a "constructive contribution" to the government, Conte said, but stressed the party is "not willing to write a blank cheque".

The M5S stance risks leading to early elections in the autumn, ahead of Italy's scheduled general election in the spring of 2023.

The right-wing Lega party of Matteo Salvini has threatened to quit the government if the M5S boycotts the key vote, while Enrico Letta, leader of the centre-left Partito Democratico (PD), said going to the polls "would be logical" if the government falls.

Giorgia Meloni, leader of the right-wing Fratelli d'Italia (FdI) party which has remained outside Draghi's broad coalition and is leading in opinion polls, has called for immediate elections.

Draghi said in recent days that the government could not survive without the M5S but stressed that his administration would not accept ultimatums.

If the M5S ceased to back the government, Draghi said, it would be up to President Sergio Mattarella to decide the next move.

Support for the M5S under Conte's leadership has plunged over the last year and in June the party was split after foreign minister Luigi Di Maio quit the party he once led, taking dozens of parliamentarians with him.

"Not voting for confidence in the government is a serious matter" - Di Maio said on Wednesday - "A government crisis right in the middle of a war is a clear act of irresponsibility, and condemns the country to the abyss."