Former Pope Francis has renewed his invitation for people to pray for Benedict and “accompany him in these difficult hours”.
The former pope is “absolutely lucid and alert” and his condition is serious but stable, the Vatican has said.
The update comes a day after Pope Francis said his predecessor, Benedict XVI, was “very sick” and asked people to pray so God would comfort him “to the very end”.
Vatican spokesman Matteo Bruni said: “The Pope Emeritus was able to rest well last night. He is absolutely lucid and alert today, although his condition remains serious, the situation at the moment is stable.
“Pope Francis renews his invitation to pray for him and accompany him in these difficult hours.”
The current pope did not elaborate on Benedict’s condition when he appealed for people to pray for him at the end of his general audience on Wednesday.
A spokesperson said he was receiving constant medical care and his condition was “under control”.
Benedict became the first pope in some 600 years to resign in 2013, due to deteriorating” health, with the former pontiff taking the title pope emeritus.
He has been living in the Vatican and dedicating his life to prayer and meditation, but has become increasingly frail in recent years.