The deal helped thaw diplomatic relations between China and the Vatican, according to a monitoring group.
The hackers are thought to come from the RedDelta group in which the alleged group began their cyberattack operations in May with an eye on September talks.
Next month, the Vatican and China are expected to engage in discussions to renew a provisional agreement on bishop appointments.
That was according to a Tuesday report by the US-based Recorded Future, which tracks state-backed cyberattacks.
The cyberattacks targeting the Vatican were first reported by the New York Times.
The Vatican had no immediate comment. The Chinese foreign ministry denied any involvement, calling the report ‘’groundless speculation.’’
Recorded Future said that the Hong Kong Study Mission to China — a key link between the Vatican and China — and the Pontifical Institute for Foreign Missions also were targeted.
‘’The suspected intrusion into the Vatican would offer RedDelta insight into the negotiating position of the Holy See ahead of the deal’s September 2020 renewal,’’ the report said.
It also could provide ‘’valuable intelligence’’ about Hong Kong-based Catholic entities’ position on the pro-democracy movement.