Yemeni Shi’ite rebels shot dead an accused government collaborator in their war with Sanaa, the interior ministry said on Sunday, in one of the first signs of violence since a truce deal to end the northern insurgency.

Yemeni President Ali Abdullah Saleh declared the war over on March 19 following a February truce with northern rebels whose fight drew in neighbouring oil exporter Saudi Arabia last year, and analysts have said the truce appeared to be holding.

The Interior Ministry said that some of the rebels, who have fought the government on and off since 2004, had opened fire on two men in the Saada region, where most of the fighting took place. One died while the other was in critical condition.

“Houthi rebels targeted the two young men as revenge for cooperating with the government during the war on Houthi rebel strife in the Saada province,” the Interior Ministry said in a statement on its web site.

Yemen, struggling to stabilise a fractious country strategically located next door to the world’s largest oil exporter, jumped to the forefront of Western security concerns after al Qaeda’s Yemen-based regional arm claimed responsibility for an attempted December attack on a U.S.-bound plane.

Western countries and Saudi Arabia fear al Qaeda is exploiting the instability on multiple fronts in Yemen to recruit and train militants for attacks in the region and beyond.

Analysts say the truce deal between the government and northern rebels was unlikely to last as it does not address rebel complaints of discrimination by Sanaa. Previous truces have not lasted.

A member of a committee overseeing the truce said he did not expect violence to spread after the shooting, adding that it would be addressing revenge cases with a view toward containing any feuds.

“The incident was contained, and there is no fear of an outbreak of acts of violence. We will be resolving cases of revenge,” the committee member said.

Yemen, in addition to its conflict in the north that has displaced 250,000 people, is also trying to contain a separatist movement in the south that has escalated in recent weeks, leaving a trail of dead and wounded and raising fears of a new insurgency even as violence in the north fades.

(Reporting by Mohammed Ghobari; Writing by Cynthia Johnston)