TUNIS, Tunisia (AP) — Tunisia's main labor union called on Wednesday for a nationwide strike next week, a move likely to exacerbate tensions with the Islamist-led government.

The decision by the General Union of Tunisian Workers to go on strike Dec. 13 comes after branches of the union in four provinces already announced plans for a general strike Thursday.

The strike plans follow an attack on union activists by members of the Committee to Protect the Revolution, a group that is supportive of the Ennahda party, the moderate Islamist faction which dominates the coalition government. Ennahda won elections after Tunisians overthrew their longtime dictator in January 2011.

Despite the transition to democracy, the economy has struggled, frustrating many Tunisians — and adding to tensions between the ruling party and the union.

After the attack on its members Tuesday, the union called for the dissolution of the pro-government group, claiming it has been linked with a number of violent actions around the country. According to a spokesman, Ifa Nasr, the union holds the government responsible for the "savage aggression" against its members.

Ennahda has condemned Tuesday's violence and promised an investigation, while calling on all parties to seek common ground in the national interest.

Last week, a general strike in the province of Siliana degenerated into five days of clashes with police.