Premier Romano Prodi survived a second do-or-die ballot in as many days on Friday after a foreign military mission financing bill was put to a confidence vote in the Senate.
The centre-left government won with 161 votes, one more than was necessary for the vote to be valid.
The Silvio Berlusconi-led opposition boycotted the ballot in protest.
The bill extends the financing of Italy's military missions abroad until the end of the year and includes funds for organising the withdrawal of Italian troops from Iraq, a pullout which is to be completed over the next five months. On Thursday evening, a section of the bill covering Italy's mission in Afghanistan was also put to a Senate confidence vote, which the government won with 159 votes.
However, the outcome was contested by the opposition, which argued that the quorum was 160 votes.
The government was forced to resort to the confidence votes in order to keep rebel pacifists in line.
Italy currently has about 1,800 soldiers deployed in Afghanistan, where they are part of a NATO-led stabilisation force.
But staunch pacifists, mainly from the Communist Refoundation Party (PRC) and the Green party, want Italy to pull out of Afghanistan on the grounds that it has become too dangerous to remain. They have been pushing for a reduction in troop numbers as a first step towards an eventual withdrawal.
A total of 16 rebel senators warned the government they would vote against continuing funding for the Afghanistan mission and themselves urged the use of a confidence vote. The pacifists said that in this way, they would be voting on the government and not on the mission and that this
would "ease their consciences".
But the two confidence votes and the quorum row highlighted the fragility of Prodi's government, which hangs by a thread in the Senate.
Prodi's disparate nine-party coalition won the narrowest of victories against Berlusconi's alliance in the April general election.
The premier has a relatively solid majority in the House, where the mission financing measures were approved last week using normal voting procedures, but only two more seats than Berlusconi in the Senate. The opposition joined the majority in approving the Afghan mission in the House but refused its help in the Senate after the government announced it was resorting to a confidence vote.
Friday's vote was the sixth confidence one called by the two-month-old government, which would be forced to resign if it lost such a ballot.
The opposition protested that confidence votes showed the government was not self-sufficient and was unable to hold its coalition together in the Senate, particularly on foreign policy issues.
It accused Prodi of abusing parliamentary procedures and said it would protest to President Giorgio Napolitano. Senate Whip for the rightist National Alliance (AN) Altero Matteoli said that "in September, we will ask for a meeting with President Napolitano because one of the two parliamentary chambers cannot continue to be annulled by these confidence votes".
"Prodi cannot strangle debate in the Senate... It is an unacceptable way to proceed," he said.
Members of the governing coalition pointed out that the Berlusconi government resorted to confidence votes 46 times during its five years in power. But Senate Speaker Franco Marini, a member of the centre left, also warned the government that "when confidence votes are excessive, it creates tensions".
Democratic Left Senator Anna Finocchiaro, whose party is the largest in government, agreed that the government could not continue calling confidence votes.
"This will be the last time," she said.
