US President George Bush is recovering after undergoing a 28-minute colonoscopy at Camp David presidential retreat. During the intervention, Bush was placed under full anaesthesia and he handed executive powers to Vice President Dick Cheney for two hours under the rarely invoked 25th Amendment.

According to White House spokesman doctors removed five small and harmless polyps, all less than 10 millimetres in size, in the latest examination.

"All were less than 1 centimeter (about four-tenths of an inch) and none appeared worrisome," White House spokesman Scott Stanzel said.

Results from precautionary biopsies of the new polyps are expected in two to three days.

After about 90 minutes of recover, Bush was "in good humour" and resuming his normal activities, Stanzel said. The president, 61, was expected to go bicycling later Saturday on the Camp David estate in the mountains of western Maryland.

The procedure was performed by a team of doctors from the National Naval Medical Center at Bethesda, Md. under the supervision of Dr. Richard Tubb, the president's doctor.