By Philip Pullella and Angelo Amante

ROME (Reuters) -Pope Francis' recovery from surgery is going well but doctors advised him not to deliver his Sunday blessing from a hospital balcony to avoid strain on his abdomen.

Briefing reporters at the Gemelli hospital on Saturday, chief surgeon Sergio Alfieri also said the 86-year-old had agreed with doctors to stay there for at least all of next week.

Francis underwent a three-hour operation to repair an abdominal hernia on Wednesday.

"Only three days have passed. We asked the Holy Father to be prudent and avoid the strain (of standing at the balcony)," Alfieri said. "Each time he gets out of bed and sits in an armchair puts stress on the abdominal walls."

A mesh prosthetic was inserted into the abdominal wall to help it heal and doctors want it to settle and attach properly to avoid another operation if it breaks, he added.

"You can understand how that would not be pleasing for him, and for me," Alfieri joked.

PORTUGAL, MONGOLIA TRIPS STILL ON SCHEDULE

Vatican spokesperson Matteo Bruni said the pope would say Sunday's traditional noon Angelus prayer in his hospital suite and the faithful could say it at the same time.

Alfieri said the pope was taken off intravenous tubes on Friday and had started a semi-liquid diet. All medical parameters were within the norm, there were no cardiac problems and complete healing of the abdominal scars would take about three months, he added.

The Vatican said blood test results were good and chest X-rays showed no problems.

Francis had part of one lung removed because of an illness when he was 21-year-old in his native Argentina.

Doctors had said after the operation that the pope should have no limitations on travels and other activities after recovery. He has trips to Portugal on Aug. 2-6 for World Youth Day and to visit the Shrine of Fatima, and to Mongolia Aug. 31-Sept. 4, one of the remotest places he will have visited.

Bruni reiterated that all audiences had been cancelled until June 18 but after that the pope's schedule would remain for now.

The pope traditionally takes all of July off, with the Sunday blessings being his only public appearance, so he will have the entire month to rest before the Portugal trip.

(Reporting by Philip Pullella and Angelo Amante; Editing by Hugh Lawson and Andrew Cawthorne)