Mumin was initially arrested in October last year after the government announced a crackdown on media outlets that publish what it deems propaganda for the Islamist militant group Al-Shabab.
Last month a court sentenced Mumin to two months in prison, but in a surprise move he was released shortly after the ruling, with officers saying he had already spent time in jail.
On Tuesday however, the office of the attorney general said Mumin's release had no legal basis.
"The commanding officer and other officials of the central prison in Mogadishu defied the court order," it said in a statement.
"The Somali police forces in response to the orders of the judiciary... returned him to prison on the 23rd of February," the statement added.
Mumin is the secretary general of the Somali Journalists Syndicate (SJS), which has been campaigning for his release.
In a text message sent to AFP on Wednesday, SJS president Mohamed Ibrahim said Mumin's arrest was "unlawful and has no place in the Somali law".
"We condemn it and call for his unconditional release."
The case has been widely criticized by rights campaigners and media advocacy groups, who had called for the charges to be dropped ahead of the sentencing.
Amnesty International, Human Rights Watch and the International Press Institute said Mumin faced ongoing threats and persecution by Somali authorities for advocating the right to freedom of expression.
"Continuing his prosecution not only casts a chilling effect on media freedom and journalism, but it also significantly contributes to the closing civic space in the country," they said in a joint letter to Somalia's attorney general in December.
Media watchdog Reporters Without Borders, known by its French acronym RSF, ranks Somalia 140th out of 180 countries on its global list of press freedom, with more than 50 journalists killed in the country since 2010.
The nation of 17 million people is the most dangerous country for journalists in Africa, according to RSF.
The main threat is from Al-Qaeda-linked Al-Shabab fighters who are trying to overthrow the internationally backed government in Mogadishu, though Somali authorities are also accused of numerous violations.
Somalia Re-Jails Journalist
FILE: Abdalle Ahmed Mumin poses outside the Banadir regional court headquarters in Mogadishu. Taken Jan. 4, 2023.
Somali journalist Abdalle Ahmed Mumin, who was freed from jail last month following his detention on security charges has been arrested again, the authorities said, calling his release illegal.
MOGADISHU —