Werribee zoo's oldest male lion dies

A Melbourne zoo has farewelled its oldest male lion, with 15-year-old Johari dying under anaesthetic for a medical examination.

Werribee Zoo's oldest male lion, Johari, has died following poor health over the past two weeks. (AAP)

The oldest male lion at a Melbourne zoo has died after his health deteriorated in the past two weeks.

Werribee Open Range Zoo's 15-year-old Johari died on Wednesday while under general anaesthetic for an examination to investigate the cause of his recent lethargy and anaemia.

An autopsy and independent peer review process will be done.

"There are many heavy hearts at Werribee today," zoo director Glen Holland said in a statement.

"He leaves a legacy of 11 cubs, some of which will continue to contribute to the future of this species through our regional breeding program."