Italy has formally withdrawn from China's vast Belt and Road infrastructure initiative, more than four years after becoming the only G7 nation to sign up, a government source said Wednesday.

The long-expected decision was communicated to Beijing three days ago, according to Italian newspaper Corriere della Sera, without any official statement from either side.

An Italian government source confirmed to AFP that Rome had pulled out, without giving details beyond saying it was done in such a way as to "keep channels of political dialogue open".

Before coming to power last year, Prime Minister Giorgia Meloni said the decision by a previous government to join in 2019 was a "serious mistake".

Critics have denounced the trillion-dollar investment scheme as a predatory "Trojan horse" aimed at buying political influence.

Italian Foreign Minister Antonio Tajani said in September that membership "has not produced the results we were hoping for".

The deal was due to automatically renew in March 2024 unless Italy opts out by the end of this year.

But Rome has been wary of provoking Beijing and risking retaliation against Italian companies.

Meloni told reporters at the G20 summit in Delhi in September that month that should Rome leave the project, it "would not compromise relations with China".

AFP