By Giselda Vagnoni and Giuseppe Fonte
ROME (Reuters) - Italy's new parliament sat on Friday for the first time since an inconclusive general election produced a political stalemate that meant deputies and senators were unable even to elect speakers for either chamber.
The February election gave the center left a majority in the lower house but not in the Senate, leaving it unable to form a government and raising the specter of a return to the polls and the threat of renewed market turmoil.
Center-left leader Pier Luigi Bersani has so far ruled out any deal with Berlusconi's center-right bloc, the second-biggest force in parliament. But his overtures to the major new force in Italian politics - Beppe Grillo's anti-establishment 5-Star Movement - have been rebuffed.
"We are ready for anything," Roberta Lombardi, the 5-Star Movement's leader in the lower house, told reporters when asked if she was prepared to go back to the ballot box.
Only once the two speakers have been elected can President Giorgio Napolitano begin formal consultations with party leaders to see if there is any prospect of forming a government.
But in a stark symptom of the stalemate, the 630 lower house deputies and 315 senators sitting on Friday failed to elect either. Voting in both houses will resume on Saturday.
After the votes, Berlusconi accused Bersani's Democratic Party (PD) for "irresponsible tactical maneuvers" that "ignore the election result," according to a statement posted on his Facebook page.
Berlusconi said a government "not only must be found but will be found" and harangued Bersani for ignoring his overtures to form a left-right government.
Businesses, bankers and foreign governments have all voiced hope that Italy can form a government capable of reforms needed to lift the euro zone's third-largest economy out of stagnation.
The fiery Grillo has promised not to support any government not led by his own movement. He has rejected any backroom deal with the parties he blames for dragging Italy into crisis.
Grillo is the only party leader who does not have a parliamentary seat as did not to run for election, choosing instead to lead his movement from beyond the corridors of power.
All other leaders were present in parliament except Berlusconi, who was discharged from hospital late on Friday after a week of treatment for an eye complaint.
An opinion poll published on Friday showed the 5-Star Movement had maintained its support in the three weeks since the election, suggesting that any return to the polls could well produce a similar result.
If the parties cannot form a government, Napolitano could ask an outsider to try to lead a technocrat administration, similar to the last one led by Mario Monti.
However, there is no guarantee the elected parties would agree to support such an arrangement this time.
As well as his health problems, Berlusconi faces two trials this month that have occupied much of his attention and contributed to the bitter political climate.
He is charged with paying for sex with a nightclub dancer when she was still a minor and, in a separate trial, is appealing against a four-year sentence for tax fraud.
While Italians and foreign investors are frustrated that the election failed to produce a clear result, the vote did inject more youth into parliament and a big increase in women.
It will be by far the youngest parliament in Italian history, thanks largely to 5-Star's 163 deputies and senators, none of whom have any previous parliamentary experience.
The lawmakers' average age of 48 is lower than that of their counterparts in Germany, France, Spain, Britain and the United States. The proportion of women has jumped to around 31 percent from 20 percent.
(Writing by James Mackenzie; Editing by Mark Heinrich and Robin Pomeroy)