Ms Chizuma was charged with "making use of speech capable of prejudicing a person against a party to judicial proceedings", after she claimed in the leaked audio that a top state official was "corrupt and compromised".

Her lawyer said the Anti-Corruption Bureau (ACB) boss was arrested on Tuesday just before 04:00 local time by heavily armed police who raided her home.

Local outlet Nation online has tweeted pictures of her release.

In parliament, Justice Minister Titus Mvalo told lawmakers that the arrest was “the work of those trying to frustrate the fight against corruption”.

Ms Chizuma is highly regarded for her strong stance in the fight against corruption - which has led to the indictment of the vice-president, one cabinet minister and the head of police service.

They all deny any wrongdoing.

The leaked audio started circulating on social media in April in which she was recorded speaking to a person not employed by Anti-Corruption Bureau on the fight against corruption.

Critics accused her of breaching the oath of secrecy and called for her sacking, but President Lazarus Chakwera said he would reprimand her both in private and public.

Three civil society organisations have said that the "government needs to desist from frustrating those fighting against corruption".

Last year, Malawi was ranked 110th out of 180 countries in Transparency International's Corruption Perceptions Index.