ROME (Reuters) - Italy’s coalition government comfortably won a confidence vote on Wednesday in the upper house Senate on a contested security decree, but tensions between the two ruling parties remain on a raft of issues.

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The bill, championed by Deputy Prime Minister Matteo Salvini, head of the far-right League, tightens immigration regulations, limits the right to asylum, and bolsters anti-terrorism and anti-mafia rules.

Despite some misgivings within the ranks of the League’s coalition ally, the anti-establishment 5-Star Movement, the government won the vote by 163 to 59, with only five 5-Star senators refusing to cast a ballot.

“This is a historic day,” said a delighted Salvini, who has pinned his credibility on the package he says will cut the number of migrants staying in Italy.

The bill must now go to the lower chamber for approval.

Had it lost the motion, the government would have been forced to resign.

The decision to call a confidence vote, which is a way to force legislation through by truncating debate, signaled turbulence within the coalition which took office in June and has shaken financial markets with its economic policies.

While the security bill caused some internal discomfort, there is greater friction within the government over efforts by the 5-Star to loosen time limits imposed on the prosecution of numerous crimes, including corruption.

The League says easing the statute of limitations means defendants could face unacceptably long legal battles. Five-Star says that as things stand too many cases are rubbed out without a verdict ever being reached.

Corriere della Sera newspaper quoted anonymous League sources as saying there was a growing prospect of a snap election in March.

Salvini looked to calm the tensions, telling reporters: “I am convinced that within a few hours we will have reached a deal (on the statute of limitations). People who have common sense always strike a deal.

“The jackals should resign themselves to the fact that this government will carry on working for the next five years.”

Other policy differences are straining the coalition, including a 5-Star proposal to introduce an income support scheme next year for Italy’s many poor and unemployed.

That was a key 5-Star election promise and was included in the 2019 budget. However, the European Union has told Rome to reduce its spending plans and the League has questioned the welfare reform.

League politician Giancarlo Giorgetti said at the weekend that implementing the “citizens’ wage” would be “complicated”.

5-Star head Luigi Di Maio, was quoted as saying by Corriere that he was tired of all the strains: “I have been good and nice, but that’s going to stop.”