Prince Philip 'progressing satisfactorily' after op
The Duke of Edinburgh is "progressing satisfactorily" after an exploratory operation on his abdomen, Buckingham Palace has said.
The palace said the results from the surgery would now be analysed.
Prince Philip, who will be 92 on Monday, was admitted to the London Clinic on Thursday and is expected to stay in hospital for about two weeks.
The Queen continued with engagements, officially opening the BBC's rebuilt Broadcasting House in central London.
The monarch, who is said to be concerned and being kept informed, will spend the weekend at Windsor, said BBC royal correspondent Peter Hunt.
Prince Philip was said to be "comfortable" and the treatment went "as planned", added our correspondent.
Buckingham Palace said on Thursday the hospital admission was pre-arranged and not an emergency.
It issued a short statement after the surgery, and said the duke "has had an exploratory operation following abdominal investigations. At this early stage he is progressing satisfactorily.
"Further updates will continue to be issued when appropriate."
The duke was admitted straight after a Buckingham Palace garden party in the afternoon where guests said he showed no signs of being unwell.
The palace said earlier he would undergo the surgery under general anaesthetic.
In the past week, the duke has been having unannounced "abdominal investigations" at the hospital, where police officers have been standing guard outside.
Prince Philip's grandson, Peter Phillips, said he was in "good hands".
Speaking at a show jumping event in east London, he said: "We are being kept up to date in terms of what's happening, but he's one of those people who just wouldn't want you to stop because he's gone into hospital."
The Duke of Edinburgh had been expected to join the Queen for her visit to the BBC.
During her visit the Queen made a live broadcast on BBC Radio 4, in which she officially declared the central London site open.
Before she unveiled a plaque, BBC Trust chairman Lord Patten wished the Duke of Edinburgh a quick recovery from his operation.
Lord Patten and BBC director general Tony Hall met the Queen and escorted her on the first part of her visit.
She started the tour, her first visit to the corporation's recently expanded headquarters, by visiting BBC Radio 1 and the station's Live Lounge to watch a performance by The Script.
Afterwards, she met BBC newsreaders Huw Edwards and Sophie Raworth and weather presenter Carol Kirkwood at the start of a tour of the BBC newsroom.
The guided tour took her to look through the glass during a News Channel broadcast.
After leaving the basement-level newsroom, the Queen met news presenter David Dimbleby and Strictly Come Dancing trio Sir Bruce Forsyth, Tess Daly and Claudia Winkleman in the ground-floor reception.
In the building's Media Cafe, which is normally open to the public but was closed for the duration of the visit, newsreader Fiona Bruce, Radio 1 DJ Greg James and actress Anne Reid were introduced to the Queen.
The Queen had previously visited Broadcasting House on five previous occasions but those were all before the BBC's extensive project to overhaul, modernise and expand the building to accommodate staff being moved from Television Centre, which closed in March.
The building is now home to more than 30 domestic and World Service radio stations, three 24-hour TV news channels, all of the BBC's main news bulletins and is the workplace for 6,000 BBC staff from the BBC's television, radio, news and online services.