Updated

A spokesman for an ultraconservative Muslim movement says clashes between his group and rebels in Yemen's restive north have left four dead, breaking a fragile ceasefire.

Serour al-Wadie of the Salafi movement said Monday that the rebels shelled their district in Damaj, in Saada province.

Animosity runs deep between the Salafis and the Hawthis, rebels from a branch of Shiite Islam fighting against the government. Each camp has been accusing the other of breaching a fragile two-day government-brokered ceasefire.

Defense Ministry officials said a U.N. envoy to Yemen, Jamal Benomar, was in contact with both camps to end the fighting. The officials spoke anonymously because they were not allowed to brief reporters.

Since Wednesday, at least a hundred people have reportedly died in fighting between the two groups.