“A request to ban was submitted recently. We are awaiting the decision of the military investigative judge,” the official, who spoke on condition on anonymity, told AFP.
He said a total ban on the party was imminent.
Hizb Al Tahrir is known for focusing on unifying Muslims into a caliphate and is already banned in several countries.
The party last month successfully overturned a decision by a civil judge to ban it, and has denounced what it says is “police harassment” in Tunisia.
It released an apparently inflammatory statement saying that “the government ... knows that its time has come and that heads and hands will be cut”.
The remarks prompted a stinging rebuke from President Beji Qaid Al Sebsi, who told his national security council last week that the group’s “arrogance towards the state undermines its authority”.
The Tunisian branch of the pan-Islamic movement appeared in the 1980s but it remained on a list of banned organisations until after the 2011 overthrow of longtime strongman Zine Al Abidine Bin Ali.
The party is frequently accused of causing public disturbances with its rallies and had its annual congress cancelled in June for “security reasons.”
Thousands of Tunisians are thought to have travelled to Syria and Iraq to fight with militants such as Daesh, and the country has witnessed a string of attacks by extremists in recent years.
