At least four people have died in two days of clashes between Yemeni security officials and a Shia preacher and his followers.
Thousands of people have died in fighting between government forces and members of the Zaidi Shia sect in the remote area on the border with Saudi Arabia.
The fighters are known as Huthis after their late commander, Hussein Badr Eddin al-Huthi, who was killed by the army in September 2004.
He was succeeded as field commander by his brother Abdul Malak.
The two sides signed a Qatari-brokered peace deal in June last year, however there are problems about how it will be implemented.