Yemeni officials say clashes between Shi'ite rebels and pro-government tribes in north Yemen have killed at least 34 people in the past three days.
In the Harf Sufyan district, at least 28 people died in fighting between Houthi rebels and the government-allied Aziz tribe.
In a separate incident late Tuesday in Saada, security officials say Houthi rebels ambushed and killed a tribal chief, his son and four others.
The Houthis have denied responsibility for the attack.
The Yemeni government struck a truce with the Houthis in February, after a six-year conflict. But instability still threatens Yemen and neighboring Saudi Arabia, which was briefly drawn into the conflict last year when rebels seized Saudi border areas.
The Houthi rebels complain of socioeconomic and religious discrimination at the hands of the government, but the government denies the accusations.
Some information for this report was provided by AFP and Reuters.