The Vatican charged Chinese authorities on Saturday with breaking a bilateral agreement on bishop appointments by installing a bishop in a diocese that was not recognized by the Holy See.

According to a statement, the Vatican learned of the installation of a bishop from another city as an auxiliary bishop in Jiangxi with “surprise and regret.”

The unauthorized installation appeared to be one of the most serious violations of a 2018 agreement between the Vatican and Beijing on the appointment of bishops.

The accord, which some Catholics have denounced as a sell-out to China’s Communist authorities, was last renewed for a two-year period in September. Its details are still secret.

Jiangxi is not recognised as a diocese by the Vatican, the statement said, adding that the installation did not “conform to the spirit of dialogue” that both sides had agreed to in 2018.

It said, without elaborating, that the installation followed “strong pressure from local authorities”. The Vatican was expecting an explanation from Chinese authorities and was hoping that the “similar episodes are not repeated,” the statement said.