* 55 Salafis dead in 4 days of fighting - Salafi spokesman
* Shi'ites accuse Salafis of bringing in foreign fighters
* Saada province outside Yemeni government control
Shi'ite Muslim Houthi rebels pressed their offensive on Saturday against a town in north Yemen held by their Sunni Muslim Salafi rivals, a Salafi spokesman said, bringing the total death toll in four days of sectarian clashes to 55.
Spokesman Serour al-Wadei denied a statement on the Yemeni defence ministry website saying that the fighting in the town of Damaj had ended on Friday afternoon and that the Yemeni army had taken up positions in the troubled area.
The spokesman for the puritanical Sunni Muslim group told Reuters the Houthis, using rockets and tank shells, had killed 15 more Salafis and wounded at least 30 in their latest attack on Damaj, which lies in the mountainous Saada province that has long been outside Yemeni central government control.
Houthi officials could not be reached for comment. There was no independent account of Saturday's clashes and no immediate report of any Houthi casualties.
Saada is the base for a long-running Houthi rebellion against the Sanaa government. Saudi Arabia's military intervened in 2009 before a ceasefire took hold the year after. The province has since fallen openly into Houthi hands with a Houthi-imposed governor.
The latest fighting erupted on Wednesday despite government mediation efforts to salvage a ceasefire in place for a year.
A Houthi statement on Wednesday accused the Salafis of igniting strife by bringing thousands of foreign fighters to Damaj. The Salafis say the foreigners are students there to study Islamic theology in a seminary built in the 1980s.
The Salafis say Damaj, which is near the Houthi-controlled city of Saada near the Saudi border, has been under rebel siege for weeks and say their rockets have hit, among other targets, student dormitories at a religious school.
The Houthis blockaded Damaj for weeks last year, accusing the Salafis of stockpiling weapons, a charge they deny.
Some Sunnis fear the Houthis want to revive the 1,000-year Zaydi Imamate, whose rulers claimed descent from the Prophet Mohammad. The imamate ended in a 1962 military coup.
Apart from the Salafi-Houthi conflict, Yemen is struggling with southern secessionists and militants of al Qaeda in the Arabian Peninsula, which has plotted attacks on U.S. airliners and targets in Saudi Arabia, the world's top oil exporter.