A member of Tunisia's security forces was killed in a firefight with a "terrorist group" at its hideout in a town near the capital Thursday, a police official said.

"Our agent died of a bullet wound in the eye sustained in clashes with a terrorist group," the official told AFP at the scene.

The interior ministry said police traded gunfire with armed "terrorists" who had taken refuge in a house in the town of Oued Ellil.

With security beefed up ahead of Tunisia's parliamentary election on Sunday, interior ministry spokesman Ali Aroui told Mosaique FM radio that police had also clashed earlier Thursday with two "terrorists" in Kebili, 500 kilometres (300 miles) south of Tunis.

The suspects were arrested after killing a private security guard in the gunfight, he said.

They had been "preparing operations in the area," Aroui said, adding that two Kalashnikov assault rifles were seized.

The parliamentary election is seen as crucial to restoring stability in the North African nation, the cradle of the Arab Spring revolutionary movements.

Since the 2011 uprising that ousted veteran strongman Zine El Abidine Ben Ali, Tunisia has seen a proliferation of Islamists suppressed under the former autocratic president and the emergence of militant groups.

The jihadists have been blamed for a wave of attacks, including last year's assassination of two leftist politicians whose murders plunged the country into a protracted political crisis.

Jihadist groups have over the past three years killed dozens of Tunisian soldiers and police, especially in violence in a remote mountain region on the border with Algeria.