Italy has withdrawn from China's vast Belt and Road infrastructure initiative (BRI), more than four years after becoming the only Group of Seven nation to sign up, a government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

The long-expected decision was quietly communicated to Beijing three days ago without any official announcement, according to the Corriere della Sera daily.

An Italian government source confirmed on Wednesday that Rome had pulled out, giving no details beyond saying it was done in such a way as to "keep channels of political dialogue open."