ROME (Reuters) - Italy's parliament is due to vote on a justice reform bill on Wednesday which would cut the length of many trials and end a bribery case against Prime Minister Silvio Berlusconi.

If approved, the provision would shorten the statute of limitations and would kill the case in which Berlusconi is accused of paying British lawyerDavid Mills a $600,000 bribe to give false testimony about his business dealings.

It forms part of a broader program launched by Justice Minister Angelino Alfano, presented by the government as reform of Italy's dysfunctional justice system but viewed by critics as a plan to keep Berlusconi out of jail.

Opponents have protested outside parliament for several days and the debate inside the building has often been heated.

Center-left parties have used filibustering tactics against the bill which they say flouts the constitutional principle that everyone is equal before the law.

The debate will continue in the lower house on Wednesday, with a vote due in the evening.

"We want to reiterate that it's not just laws but also the principles of the constitution that the government is trampling on," said Dario Franceschini, lower house leader of the largest opposition party, the Democrats of the Left.

Berlusconi's bribery case is due to run until January or February 2012, but if the bill is approved it would shorten that by about 8 months, ending the trial by the summer before a sentence has been handed down.

Alfano, a 40-year-old Sicilian often cast as Berlusconi's political heir, has denied that his reform of Italy's notoriously snail-paced justice system is aimed at getting Berlusconi off the hook.

But the timing of the legislation coincides with the launch of several cases against the prime minister, including a trial in which he is accused of paying for sex with "Ruby," an under-age Moroccan dancer.

The trials were previously suspended by a measure passed by his government which allowed him to claim that his official duties meant he did not have enough time to prepare his defense and could therefore claim immunity from trial while in office.

The constitutional court ruled against that measure in January, prompting magistrates to re-open fraud and bribery trials and bring the prostitution case to court.

On Monday, Berlusconi launched a bitter attack against the magistrates as he emerged from a hearing in a tax fraud trial, saying he was the victim of an attempt by leftist enemies to eliminate him from the political scene.

If the bill is approved in the lower house, where Berlusconi has a slim majority, it will go to the Senate for a final vote.

(Writing by Catherine Hornby; Editing by Janet Lawrence)

Source: Reuters US Online Report World News