Boukary Daou spent a month in jail after being arrested in March 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.

Daou's lawyer Hamidou Diabate said the court "found that the case against my client was zero. So, no trial, no conviction -- my client is free."

The media had 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.

His lawyers had asked for the case to be thrown out of court, arguing that laws regulating the press had not been applied properly.

Daou said he was "deeply moved", adding: "I thank all the press for their support. I thank my lawyers. This is a victory for freedom of the press in Mali."

"I am proud of the Malian justice system, which resisted the pressure and applied the law. The file is closed and Daou is definitely free," his lawyer added.

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.