“The check-up and observations went well,” his foundation said in a statement.

His trip came after he lost a case last month at the Constitutional Court, where he had tried to overturn a ruling that he must return to prison.

The Constitutional Court ruled that Zuma had been granted medical parole unlawfully.

The prisons department has now given the 81-year-old until Friday to submit reasons why he should not serve out the rest of his 15-month sentence.

Zuma was released in September 2021 after serving less than eight weeks.

He was given parole by the former head of the prison service, Arthur Fraser, who is regarded as Zuma's ally.

The former president had been convicted of contempt, after refusing to co-operate with an anti-corruption enquiry during his term in office.

Zuma is also facing a separate corruption and fraud trial related to an arms deal in the late 1990s.

The Jacob G Zuma Foundation said his return from Russia was “also necessitated by the private prosecution matter which will be sitting in the Pietermaritzburg High Court” this Friday.