The 81-year-old was operated on at Sydney’s Royal North Shore private hospital yesterday afternoon after complaining of feeling unwell over the weekend.

A spokesperson for Howard said he was recovering well, with his wife Janette by his side.

Appendicitis, which usually causes pain in the abdomen, is an inflammation of the appendix.

Surgery to remove the organ is one option for treatment. However, it can also sometimes be managed with antibiotics.

Appendicitis is more common in people under the age of 30, and the cause is still unclear.

The mortality rate is low, but it increases with age because of the risk of misdiagnosis.

Howard served as Australia’s 25th prime minister between 1996 and 2007.

-AAP