SANAA, Aug 13 (Reuters) - Fighting between Shi'ite Muslim Houthi rebels and Sunnis loyal to the Islamist Islah party has killed at least 15 people in Yemen's al-Jouf province, tribal sources said on Wednesday.
The fighting in northern Yemen, which has taken on a sectarian tone, is further destabilising the country battling a secessionist movement in the south and the nationwide spread of an al Qaeda insurgency.
Ceasefire agreements reached with government intervention have repeatedly failed to stop the conflict between the two sides. At least 200 people were killed and more than 35,000 displaced last month when Houthi rebels overtook Amran, 50 kms (30 miles) north of the capital Sanaa.
According to tribal sources, fighting erupted in the northeastern province of al-Jouf on Tuesday night with both sides using heavy weaponry including tanks that were previously captured from the army.
The Houthis, named after their leader's tribe, have said their fight was against rivals loyal to the Islamist Islah party - which has links to the Sunni Muslim Brotherhood - rather than the government.
The Houthis, who control much of the northern Saada province bordering Saudi Arabia and next to al-Jouf, are trying to consolidate their power in the north as the country moves towards a federal system that gives more power to regional authorities.
U.S. allied Yemen, an impoverished country of 25 million that shares a long border with the world's top oil exporter Saudi Arabia, has been in turmoil since 2011 when mass protests forced the veteran president, Ali Abdullah Saleh, to step down. (Reporting by Mohammed Ghobari; Writing by Maha El Dahan; Editing by Yara Bayoumy)