By Massimiliano Di Giorgio
ROME (Reuters) - Italy's Senate will hold an open vote next month on whether to expel Silvio Berlusconi from parliament because of a tax fraud conviction after an upper house committee narrowly rejected the former prime minister's bid to make the ballot secret.
The decision has been the subject of intense wrangling, with the billionaire media magnate's political enemies fearing a secret vote might allow him to escape expulsion through backroom dealings.
A special Senate panel voted by 7 to 6 in favor of an open vote, overruling objections from Berlusconi's People of Freedom (PDL) party, which argued that votes on individual senators are traditionally held in secret.
"The panel has voted but it's given birth to a constitutional monster," PDL Senator Anna Maria Bernini told reporters. "This was a decision aimed against one person."
No date has yet been set for the vote, but the Senate agenda is full until November 22, requiring a change to the timetable if the ballot is to be held before then.
Berlusconi is expected to lose his seat in the upper house after Italy's top court found him guilty in August of being at the center of a giant tax fraud scheme at his Mediaset television empire.
But the expulsion procedure is proving long and divisive, with the PDL repeatedly trying to delay the vote, which would strip its leader of parliamentary immunity and leave him open to arrest in a string of other cases.
Wednesday's decision prompted a flood of anger from Berlusconi's supporters, stoking tensions in Prime Minister Enrico Letta's unwieldy coalition between the PDL and the center-left Democratic Party (PD).
"Democracy was murdered in the Senate today," said Daniela Santanche, one of the 77-year-old leader's most hardline loyalists. "How can anyone still maintain on the basis of some false idea of stability that this government serves the country?"
The full Senate, where there is a majority in favor of expelling Berlusconi, must vote before the former prime minister can be stripped of his seat under a law passed last year banning convicted criminals from parliament.
However the showdown has been delayed by heated disagreement between the PDL and Letta's PD, and aggravated tensions between Berlusconi hardliners pressing for a rupture with Letta and moderates around PDL secretary Angelino Alfano who want to keep supporting the government.
"The decision of the Senate panel should be respected," PD secretary Guglielmo Epifani said in a statement. "People should lower their tone and remember that the law is supposed to be the same for everyone."
Letta, who survived an attempt to bring down the government earlier this month, has expressed confidence that he has the numbers in parliament to keep going even if Berlusconi decides to withdraw support from his coalition.
However even PDL moderates attacked the decision to hold an open vote, saying the PD had yielded to pressure from the anti-establishment 5-Star Movement of comic Beppe Grillo.
"It's an absurd decision that goes against parliamentary prerogatives and good sense," said Health Minister Beatrice Lorenzin, who along with other PDL ministers defied Berlusconi's orders to quit the government last month and forced him to drop a plan to bring down Letta.
Berlusconi, sentenced to four years in prison, commuted to a year under house arrest or in community service - protests his innocence, saying he is the victim of left-wing magistrates.
He also disputes the validity of the law under which he faces expulsion and has threatened to withdraw support for Letta if the Senate votes to throw him out.
As well as the prison sentence, the courts have also barred him from holding public office for two years, which means he will almost certainly be expelled eventually, whatever the result of this Senate vote.
The tensions over the vote have greatly complicated the task facing Letta's government, which must still pass the 2014 budget law before tackling more ambitious reforms to revive Italy's stagnant economy and cut its enormous public debt.
(Writing by James Mackenzie; Editing by Barry Moody and Angus MacSwan)