Italy's government said Thursday it would address concerns over a new bridge to Sicily, after Prime Minister Giorgia Meloni condemned a court ruling against the project as an "intolerable intrusion".

Meloni's government in August approved the 13.5-billion-euro ($15.6-billion) project to build what would be the world's longest suspension bridge connecting the island of Sicily to the mainland.

But in a ruling late Wednesday, the Court of Auditors, which oversees public spending, refused to approve the decision.

It said it would give its reasons within 30 days, but last month it had requested clarification about documentation used on the project, and on costs.

Meloni, leader of the far-right Brothers of Italy party, condemned Wednesday's ruling as "yet another encroachment on the jurisdiction of the government and parliament".

"The constitutional reform of the justice system and the reform of the Court of Auditors, both under discussion in the Senate and close to approval, represent the most appropriate response to this intolerable intrusion, which will not stop the government's action," she said in a statement.

At the same time, Matteo Salvini, head of the far-right League party who as deputy prime minister and transport minister has championed the bridge, said the ruling appeared to be a "political choice".

Yet on Thursday, after Meloni called an emergency meeting with her ministers, the government adopted a more conciliatory tone.

"We await with extreme calm the Court of Auditors' findings, to which we are confident we can respond point by point, because we have complied with the requirements," Salvini told reporters.

In a statement, Meloni's office confirmed the government would respond to each complaint, adding that "the objective... to proceed with the project remains firm".

Italian politicians have for decades debated a bridge over the Strait of Messina, a narrow strip of water between the Sicily and the region of Calabria, at the toe of Italy's boot.

"We have waited a century, and we will wait a century and two months," Salvini added.

- 'Respect for magistrates' -

The approval in August by a government committee, CIPESS, is the furthest the project has ever got.

Advocates say the state-funded project will provide an economic boost for the impoverished south of Italy.

The government also hopes the bridge can be classified as a strategic asset, with its costs counting towards the money Italy has committed to spend on defence as part of the NATO military alliance.

However, critics warn that the project risks turning into a financial black hole.

It has also sparked local protests over the environmental impact, and complaints that the money could be better spent elsewhere.

The Court of Auditors on Thursday said its decision was based on legal aspects of the approval of the bridge, not on the merits of the project.

In a strongly worded decision, it added that any criticism of its decisions "must be conducted in a context of respect for the work of the magistrates".

In three years in office, Meloni and her ministers have repeatedly taken aim at the judiciary for decisions they assert are political.

Parliament on Thursday approved a reform to separate the training, careers and status of judges and prosecutors, whom right-leaning governments in Italy have long accused of colluding to the detriment of the defence.

The reform must now go to a referendum.