Buckingham Palace was evacuated yesterday after a fire broke out and smoke billowed from a roof but fire services rapidly brought the blaze under control.
Police said no members of the royal family, celebrating 50 years of Queen Elizabeth's reign at events around the country, were in the palace at the time.
"Everyone was safely evacuated and the fire is now contained," a police spokesman said, adding that fire brigade investigators would determine the cause of the blaze.
Firefighters could be seen clambering over the roof of the 160-room building to reach a small section where flames had at one time been visible and from which smoke was still seeping an hour after the alarm was raised.
Police said there were reports the fire had broken out in the loft of the west terrace of the palace.
The Queen, at the height of her golden jubilee celebrations, had hosted a classical music concert for 12,000 people in the garden of the palace on Saturday night and is due to host a pop concert in the same place today.
Technicians and musicians, including Queen guitarist Brian May who will open today's concert with a rendition from the roof of the palace of God Save the Queen, had been at the palace for rehearsals. They were all herded away from the building.
The concert line-up will include former Beatle Paul McCartney, gothic rocker Ozzy Osbourne, Latino heart-throb Ricky Martin and pop idol star Will Young.
The concert will climax with a rendition of the Beatles classic All You Need Is Love followed by a major extravaganza using three tonnes of fireworks from the roof of the palace.
It is believed fireworks were all in place on the roof at the time the fire started.
A palace spokeswoman was unable to say what caused the fire, what damage had been done or if there were any injuries. - (Reuters)