Tunisia security forces warn of militants returning from wars
The internal security forces' national union said battle-hardened fighters "have received military training and have learnt to use all sorts of sophisticated weapons."
"The return of terrorists from hotbeds of unrest in Tunisia is worrying and could lead to the Somalisation of the country," said a statement.
Tunisia has witnessed a wave of militant attacks since its 2011 revolution, including on foreign tourists, and the United Nations estimates that there are more than 5,000 Tunisians fighting for militant groups, mainly in Iraq and Syria.
The warning came a day after Tunisian authorities said they had arrested three people including the nephew of Anis Amri, a national suspected of carrying out a deadly truck attack on a Berlin Christmas market this week.
Hundreds of people gathered outside parliament in Tunis on Saturday to protest against allowing militants to return to the country after fighting with groups abroad.
Earlier this month, President Beji Caid Essebsi said Tunisia would refuse to pardon Tunisians who fight for militant organisations.
"Many of them want to return, and we can't prevent a Tunisian from returning to his country," he told AFP, "but we will be vigilant."
Following a storm of criticism in the press and on social media, on December 15 he told Tunisian local television that "we will not be indulgent with the terrorists".
Some 800 Tunisian nationals who had fought for extremist groups abroad had since returned to the country, the country's Interior Minister Hedi Majdoub told parliament on Friday.
There are more than 5,000 Tunisians fighting for militant groups abroad, mainly in Iraq, Syria or neighbouring Libya, according to a UN working group on mercenaries.