Tunisia arrested eight Islamists arriving from its troubled neighbour Libya and said they were planning attacks in Tunisia.
"This group of eight extremists came from Libya ... planning to assassinate security officials and mount attacks against government institutions," the Interior Ministry said on Wednesday without giving details of their nationality.
The ministry added that the detainees had been trained in explosives and weapons in Libya.
With the rise in violence in its neighbor Libya, Tunisia has tightened security in anticipation of possible infiltration of armed groups.
Tunisian security forces have been battling militants from the banned Islamist movement Ansar al-Sharia, one of the most hardline groups to emerge after the 2011 ouster of autocrat Zine El-Abidine Ben Ali.
With an economy heavily reliant on foreign tourism, Tunisia has been cracking down on Islamist militants that it views as a key challenge on its path to full democracy.
One of the Arab world's most secular states, Tunisia has adopted a new constitution and a caretaker government has taken over as a way to ease tensions between a leading Islamist party and secular opponents until elections due later this year.