Italian Democratic Party (PD) leader Pier Luigi Bersani has closed the door on a governing coalition with Silvio Berlusconi and reiterated an appeal to Five Star Movement (M5S) MPs to face up to its responsibilities to voters.

Bersani's leftwing coalition won a majority of seats in the lower chamber of parliament but is 35 seats short of a majority in the upper house and needs the backing of senators from Beppe Grillo's M5S or Berlusconi's People of Freedom party (PDL) to form a government.

"We believe an agreement with Berlusconi's right is neither viable nor credible," Bersani told delegates at PD's national conference. "No cooperation is possible with he who has brought us today's storm."

A coalition with Berlusconi would be regarded as political harakiri by Bersani, as it would play into the hands of Grillo, who has built his platform on public anger at the old ruling class establishment the two politicians represent.

"If they [M5S] believe we are going to strike an agreement [with Berlusconi] they can easily target shooting cannonballs they are wrong," Bersani said.

"[Grillo] has to say what he wants to do with the more than eight million votes it won at the elections."

Grillo, has far maintained that his party will not support any government but his own. He called Bersani a "dead man talking".

"The only solution we back is a Five Star Movement government tasked with implementing without delay all 20 points listed in our manifesto," said M5S spokesman Vito Crimi.

A government of change

After the new parliament convenes on 15 March, President Giorgio Napolitano will start talks with all parties before choosing a prime minister.

The PM and his government will have to win a vote of confidence in both houses to be confirmed.

"We are ready to put before the parliament a government of change," Bersani said, presenting a list of reforms he intends to implement if chosen.

He pledged to "lead Italy out of the austerity cage" by slashing Italian bureaucracy to cut costs and redirect savings into boosting the economy.

Many of his proposals echoed those listed in Grillo's manifesto but the PD leader denied he was courting Grillo.