ROME, Dec 9 (Reuters) - Italy’s Chamber of Deputies on Wednesday gave the go-ahead for Prime Minister Giuseppe Conte to approve a contested reform of the euro zone’s bailout fund, known as the European Stability Mechanism (ESM), at an EU summit this week. Last week some 60 rebels from the co-ruling 5-Star Movement, which has always opposed the reform, threatened to vote against the government, leaving it potentially vulnerable in Wednesday’s votes in both houses of parliament. However, coalition negotiations produced a resolution which most 5-Star deputies agreed to, authorising Conte to approve the ESM changes while pursuing other reforms of EU financial management aimed at overturning austerity. At the end of a heated debate the Chamber approved the resolution by 314 votes to 239. The more eagerly awaited vote in the Senate, where Conte normally has a much slimmer majority, will be held after 1700 GMT. Assuming the government wins it, Conte will sign off on the revamped ESM at the Brussels summit beginning on Thursday. The reform, which Italy has held up for months due to 5-Star’s resistance, must then be ratified by national parliaments before it comes into force on Jan. 1, 2022. (Reporting by Gavin Jones, Angelo Amante, Giuseppe Fonte, Francesca Piscioneri