Updated

LONDON -- Former British Prime Minister Margaret Thatcher has been admitted to the hospital following a recent bout of flu, officials said Tuesday.

Prime Minister David Cameron's office said he wished the former leader a "speedy recovery."

"We understand from Lady Thatcher's office that she has been admitted to hospital for precautionary tests following her recent bout of flu," a Downing Street statement said.

Thatcher, who was prime minister from 1979 to 1990, had to skip a reception in honor of her 85th birthday last week because of the flu. She wrote a letter of apology to the 150 friends and colleagues who attended the reception, which was hosted by Cameron at 10 Downing Street.

Her son Mark Thatcher stressed to reporters after visiting her at London's private Cromwell Hospital that she was admitted for "routine tests." He did not provide details.

"It's entirely precautionary at this stage," he said, adding that his mother is in "very good spirits."

Thatcher has suffered from a series of health problems in recent years. In 2008 she became ill during a dinner at Westminster and had to spend the night in the hospital as a precaution -- she was later given a clean bill of health. A few years earlier, her doctor had advised her not to make public speeches following a number of minor strokes.

Sky News reported that Thatcher is still troubled by an infection related to the flu and her aides called in a doctor to assess her condition on Tuesday. She was then taken to the hospital for tests, the report said quoting unnamed people close to the former Conservative leader.

Her spokesmen did not immediately return calls from The Associated Press seeking details of her condition Tuesday.