An Australian cardiologist charged in Uganda with his wife's murder has been taken to hospital after falling ill in jail.

Aggrey Kiyingi suddenly became ill yesterday at Uganda's Luzira maximum security prison, where he is on remand over his alleged involvement in his wife's killing.

Robinah Kiyingi, a well known lawyer and anti-corruption campaigner, was shot dead on July 11 at the gate of her home by assailants who escaped on a motorcycle.

Kiyingi was rushed under tight security to Mulago national hospital on the outskirts of the Ugandan capital, Kampala.

Uganda Prisons spokeswoman Mary Kaddu said the Australian was earlier admitted to the prison hospital suffering from malaria, high blood pressure and back ache.

But he had to be moved to the Mulago facility when his condition deteriorated.

"He has been suffering from back ache, hypertension and malaria but last night the situation got worse and he was transferred from the prison hospital to Mulago hospital, where he was admitted," Kaddu said.

She said Kiyingi underwent a full check-up and was confined to bed.

His health had since improved and he had been returned to the Luzira prison hospital, she said.

She denied the prison had lacked the drugs to property treat the Australian.

Dr Sam Kasirye, who treated Kiyingi at Mulago hospital, said the Australian was in a critical condition when he was admitted but had since improved.

Kiyingi's illness prevented him from appearing in court today for another mention of his case.

Presiding judge Justin Atukwasa ruled Kiyingi should next face Uganda's High Court on December 12.

AAP