Former prime minister Sir William McMahon's widow Lady Sonia McMahon, was reported to be admitted to an intensive care unit in a Sydney hospital.

It was reported that Nip/Tuck star Julian McMahon's mother Sonia McMahon was admitted to St Vincent's private hospital in Sydney's east over the weekend following a lung problem.

Her lungs were drained of fluid during a surgery she underwent at the hospital. According to a hospital spokesperson, Sonia, 77, was in a stable condition and she might be moved out of the ICU later today.

For several months, Sonia was reportedly battling cancer.

In 1965, Sonia McMahon had married William McMahon in Sydney. At the time of their wedding, she was 32 and he was 57.

William became prime minister in March 1971 and served his term until December 1972.

In 1971, Sonia was in limelight for wearing a revealing dress to the White House and was photographed in the company of her husband and United States president Richard Nixon.

In 1977 William McMahon was knighted and he died in 1988.