TUNIS (Reuters) - A Tunisian policeman and three Islamist militants were killed on Monday in a security operation in a remote area near the Algerian border, police said.

Tunisia is one of the Arab world’s most secular nations, and became a target for militants after being hailed as a beacon of democratic change with an uprising against autocrat Zine Abidine Ben Ali in 2011. A presidential election is to be held on Sept. 15.

“Our forces killed three terrorists after a clash that came after a 10-day follow-up as part of the pursuit of terrorist elements,” Police Colonel Houssem Jbebli said.

The dead policeman was the head of a station in the town of Haidra, he added.

Prime Minister Youssef Chahed told Reuters last week that Tunisia was still under threat from militant groups including Islamic State.

Tunisia suffered three major attacks in 2015: one at a museum in Tunis, one on a tourist beach in Sousse and one on presidential guards in the capital. All three were claimed by Islamic State.

Tourism has been recovering gradually from the effect of the attacks.