A Malian judge granted bail on Tuesday to a journalist detained nearly a month ago after publishing a letter criticising the war-torn nation's former military junta chief, his lawyer said.

Boukary Daou was taken into custody on March 6 and charged with "incitement to disobedience" over the letter objecting to the salary earned by Captain Amadou Sanogo, leader of a coup that ousted Mali's government last year.

"The court... has granted bail to my client Boukary Daou. It's official. We expect to complete the formalities and my client will pick up his belongings at the custody centre in Bamako before going home," Me Cheikh Oumar Konare said.

The media launched a nationwide strike to protest against the arrest of Daou, the editor of the Republican daily newspaper, with the campaign eventually morphing into a blackout of coverage of government activities.

Sanogo was installed in February as head of a military reform committee, a post created for him as an incentive to accept a transitional government tasked with steering the west African country to elections.

He had led a group of fellow mid-level officers to overthrow then-president Amadou Toumani Toure in March last year, upending what had been considered one of the region's most stable democracies.

The coup precipitated the fall of northern Mali to Islamist militants linked to Al-Qaeda but a military intervention by French and African troops chased the rebels from the region's main cities.

However, fighting continues in desert areas of northeastern Mali where armed Islamists are entrenched.

The Court of First Instance of the Fourth Municipality of Bamako confirmed Daou had been bailed.

"We got two undertakings before granting bail to Mr Daou: he will not publish the offending article again and that his lawyers agree to represent him wherever necessary before the trial," a court official told AFP on condition of anonymity.

Daou is due to be tried before the court on April 16.