Former British prime minister Margaret Thatcher, the country's first woman elective leader, is in an unidentified hospital recovering from surgery to remove a growth on her bladder, a source close to the family said on Friday.

After experiencing pain in her bladder earlier in the week, the 87-year-old went to hospital where she underwent a minimally invasive operation, Tim Bell, a public relations executive who once served as image maker to Thatcher, said.

"The operation was completely satisfactory. She's now recovering in hospital and as soon as she's recovered she'll go home," Bell said.

Known as the "Iron Lady," Thatcher, who stepped down in 1990, embraced free market policies, challenged trade unions and privatised many state-owned companies during her 11 years in power, polarising British voters.

Britain's only woman prime minister, who led her country in a war with Argentina over the Falkland Islands in 1982 and was close to President Ronald Reagan, was forced to step down by her own party.

Thatcher suffered a series of mild strokes in late 2001 and 2002, after which she cut back on public appearances and later cancelled her speaking schedule.

She was hospitalized in 2010 for tests relating to a flu illness.