Economy Minister Giulio Tremonti promised on Sunday to meet Italy's budget pledges after growing speculation over whether the European Central Bank may cut back its purchases of Italian government debt.

Tremonti, under mounting pressure to present a credible plan to fulfill a pledge of balancing the budget by 2013 and cutting Italy's 1.9 trillion euro debt pile, told a business conference in the northern town of Cernobbio that the target would be met.

However he admitted that a hastily put-together package of measures presented to parliament in August and now undergoing substantial revision, had been incomplete.

When you take measures in four days you can make mistakes, it's true, he told a conference discussion.

The regular Ambrosetti conference in Cernobbio near Milan this weekend has brought growing doubts about the 45.5 billion euro austerity package to a head following a week of rising market pressure on Italian government bonds.

Both ECB President Jean-Claude Trichet and Italy's head of state, President Giorgio Napolitano issued strong calls for swift action following widespread criticism of the haphazard way in which the plan was being handled.

Marco Tronchetti Provera, chairman of tyremaker Pirelli, one of the icons of Italian industry, said Tremonti's speech to the conference had been clear but it had not eliminated doubts about the gravity of the situation.

I repeat that anyone who is not concerned about this situation is making a mistake, he told reporters.

The head of Confindustria, Italy's largest employer federation also took aim at the government during the conference, saying the plans presented so far did not do nearly enough to stimulate the country's anaemic growth rates.

Underlining the growing concerns, the premium investors demand to hold Italian debt rather than benchmark German bonds rose on Friday to 331 basis points, the highest since the ECB started buying Italian paper in August.

Yields on 10-year Italian bonds ended the week at 5.29 percent, creeping back up toward the 7 percent level generally regarded as unmanageable.

ECB INTERVENTION

With the spreads over German debt widening ominously, there was growing speculation over whether the ECB would continue buying Italian debt, a strategy that has caused sharp divisions within the Frankfurt-based central bank.

The ECB has been buying Italy's bonds in the market to try to hold down yields and stop Rome's borrowing costs spiralling out of control, there has been a growing sense of frustration that the government has not done enough itself.

Our biggest concern is that the ECB might halt its purchases of Italian bonds, which would cause spreads to widen again, the head of Confindustria, Emma Marcegaglia, told reporters. In this case, Italy would have huge problems.

On Saturday, Trichet declined to comment on the bond buying programme ahead of a Governing Council meeting on Thursday.

Italy, the euro zone's third largest economy, has been dragged ever closer to an emergency that could overwhelm any existing euro zone bailout mechanisms. But there have been worries in Germany that the ECB is blurring the lines between monetary policy and governments' own fiscal responsibilities.

Italy's Foreign Minister Franco Frattini, who said on Saturday that the government was pressing the ECB to keep up the purchases, backtracked on Sunday, saying the central bank was independent and Rome was not exerting pressure.

Tremonti offered no substantial new pledges on the timing or substance of the austerity package, which has been subject of repeated changes and dispute over the past weeks.

However he repeated his longstanding call for jointly issued euro bonds, which have been rejected by Germany.

The euro bonds will absolutely be done, he said. Either we do euro bonds or we will have critical problems, he said.

Frattini told reporters the Senate would approve the new package by the end of next week and that approval from the Lower House would follow swiftly.

I don't see any reason why the government should ask for a confidence vote on the budget, he added.

(Writing by James Mackenzie, editing by Rosalind Russell)