Renewed clashes between Shiite Huthi rebels and armed tribesmen have killed 13 people in northern Yemen, tribal sources said Tuesday.

Heavy fighting erupted on Monday and continued Tuesday in Wadi Khaywan and Danan, in Amran province, between the rebels and Hashid tribesmen, sources said.

They said 12 people were killed.

And a rebels was killed in fighting with hardline Sunni Salafists in Arhab, north of Sanaa, as the two sides battled control for three hills overlooking the airport, other sources said.

The fighting in Amran first erupted on January 5 when Huthis tried to seize Hashid strongholds.

On January 8, a presidential commission brokered a truce, but the fighting soon resumed.

The Huthis attacked the Hashid in retaliation for the tribe's supporting Sunni Islamist groups fighting the Huthis in the Saada provincial town of Dammaj.

The town had been besieged by the rebels since October until troops began to deploy there on January 11 to monitor a ceasefire between them.