TUNIS: Gunmen have kidnapped dozens of Tunisians in northwestern Libya to demand the release of a local Libyan official arrested in Tunisia this week, families and locals sources said Tuesday.

An official from Sabratha, a coastal town between Libya’s capital Tripoli and the Tunisian border, was arrested along with another Libyan at Tunis airport Saturday, Sabratha’s municipal council said.

They had flown to Tunis on a visit organized by U.N., the council said. Tunisian officials were not immediately available to comment.

“Gunmen kidnapped my father. ... We talked with the kidnappers over the phone and told us they would release them only when Tunisia frees the Libyan officials arrested in Tunisia,” the daughter of one of the detained Tunisians said. “I ask the authorities to intervene.”

Mustapha Abd al-Kebir, a Tunisian activist with contacts in Libya, said dozens of Tunisians were being held in Sabratha.

Armed groups in chaotic Libya often act with impunity because of a security vacuum in which two rival governments and their armed backers fight for control of the North African state four years after Moammar Gadhafi’s fall from power.

Tunisians and other foreign nationals have been kidnapped or detained in the past to pressure their governments to release Libyans held overseas.

An armed group stormed the Tunisian consulate in Tripoli and kidnapped 10 staff this year before releasing them. Tunisia closed the consulate after the kidnapping.

Relations between the North African neighbors have become increasingly tense, with Tunisia’s government worried about spillover from the chaos that continues to plague Libya after the 2011 revolt against strongman Gadhafi.

Meanwhile, a group linked to Al-Qaeda’s North Africa branch in Tunisia says it has executed a shepherd it abducted Sunday from a zone near the Algerian border.

The Oqba Ibnou Nafaa brigade claimed responsibility for the killing on its Twitter account. It accused the shepherd of informing police about the group’s movements.

The group also claimed responsibility for the killing of two Tunisian soldiers and wounding three others who had conducted a sweep of the area following the shepherd’s abduction.