The jihadist Islamic State group on Tuesday claimed responsibility for an attack in central Tunisia that killed three policemen and wounded 12.
In a statement posted on Twitter, IS said the attack in the Sidi Bouzid region was carried out by "two soldiers of the caliphate who attacked two military sites with small arms."
The group, which claimed a March attack on the Bardo National Museum in Tunis that killed 21 foreign tourists and a policeman, said it had "killed or wounded more than 20 soldiers or national guard members" in Monday's violence.
Three policemen and a jihadist were killed when national guardsmen, acting on a tip-off, tried to ambush two armed men who were allegedly planning attacks, the interior ministry said.
"The national guard attempted to ambush at dawn two terrorists on a motocycle in Sidi Ali Ben Aoun after obtaining information that (they) were about to launch an operation," ministry spokesman Mohamed Ali Aroui told AFP.
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He said two officers were killed in the ensuing shootout, and that the militants fled before killing a third policeman who had been going to work.
They were pursued by an elite unit of the national guard, Aroui said.
"One of the terrorists was exterminated, the second was wounded and arrested. He is in a serious condition," he added.
The interior ministry initially blamed the violence on Tunisia's main jihadist group, the Al-Qaeda-linked Okba Ibn Nafaa Brigades, which it has accused of being behind several recent attacks.
Tunisia has seen a surge in radical Islam since veteran president Zine El Abidine Ben Ali was ousted in a 2011 revolution.
Dozens of members of the security forces have been killed since then in jihadist attacks.