ROME (Reuters) - Silvio Berlusconi’s Forza Italia (Go Italy!) party on Friday accused the far-right League of breaking ranks with its conservative ally during a vote to select the speaker of the Senate.

General view of the Senate during the first session since the March 4 national election in Rome, Italy March 23, 2018. REUTERS/Remo Casilli

The clash between the two parties came on the first day of the new parliament following national elections in March and could mark a premature end to the coalition that won the most seats but fell short of a working majority.

If the alliance collapses it will increase the possibility of a government made up of the League and the anti-establishment 5-Star Movement -- an option viewed with alarm in Brussels by markets because of both parties’ hostility to European Union budget rules.

In a toughly worded statement, Forza Italia accused the League of plotting for this outcome in not picking the pre-agreed Forza Italia conservative candidate for the prestigious upper parliamentary house position.

The League’s move was “a hostile act ... which breaks the unity of the centre-right coalition and reveals the plan for a League/5-Star government,” Forza Italia said.

Tensions frequently surfaced between the two conservative parties during the election campaign but few expected the alliance to face a break-up so soon after the vote.

5-STAR VETO

Electing the speakers of the two houses is the first task of parliament and negotiations between the parties broke down on Thursday when 5-Star - the largest single party at the election - refused to back Berlusconi’s pick for the Senate job.

Berlusconi had backed Forza Italia veteran Paolo Romani, but the 5-Star Movement, whose appeal is based on a pledge to clean up politics, rejected him because he has a conviction for embezzlement.

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League leader Matteo Salvini sought to break the deadlock on Friday by saying his party would back another Forza Italia senator, Annamaria Bernini.

But he did so without the consent of Berlusconi, prompting the unexpected rupture between the allies.

The election of the speakers precedes formal consultations to cobble together a government and can serve as a sign as to what kind of ruling alliance can be formed.

Salvini and 5-Star leader Luigi Di Maio are both claiming the right to be named prime minister - Di Maio as head of the largest party and Salvini as head of the leading party in the centre-right coalition.

However, Salvini’s chances would all but disappear if the coalition were to fall apart.

Di Maio tweeted after Berlusconi’s statement that 5-Star was willing to back Bernini, or an alternative centre-right candidate with “a similar profile” as Senate speaker, as the League proposed.

Salvini responded that in return the League would support a 5-Star candidate as speaker of the lower house Chamber of Deputies.

It is as yet unclear if Forza Italia’s broadside is the beginning of the end for the centre-right, or merely an attempt by the 81-year-old Berlusconi to reassert his position after his party’s disappointing election performance.

The League won 17.4 percent of the vote, overtaking Forza Italia which took 14 percent, while 5-Star won 32.7 percent.

Formal consultations on forming a government are expected to start in April, when party delegations will meet with 76-year-old President Sergio Mattarella, who will try to broker a deal.

The process could take weeks or even months, and political sources have said a breakthrough is unlikely to come before regional elections slated for the end of April.

The first day of voting for the speakers of the two chambers ended without any candidate achieving the required majority. The process will continue on Saturday and could last well into next week in the lower house, where a larger majority is required than in the Senate.