Heavy fighting pitted army troops and counter-terrorism units against the rebels in the Al-Shafia and Wadi Nushur (Nushur Valley) areas of Saada province, the sources said on Wednesday.
Government forces were trying to advance towards the Wadi Nushur stronghold of the father of slain preacher Shaikh Husain Badr al-Din al-Huthi, who was killed by the Yemeni army last year.
Authorities say al-Huthi has become the spiritual leader of his son's followers from the Faithful Youth movement.
Both military and tribal sources said at least 30 people from both sides were killed or wounded in Wednesday's fighting, but could not give a more specific breakdown.
Around 110 people had been reported killed, and dozens more wounded, since the violence erupted in the mountainous region on 28 March.
The deputy governor of Saada, Hasan Manaa, escaped an ambush laid by the rebels in the town of Saada on Wednesday, a source close to Mannaa said.
Five of Manaa's bodyguards were seriously wounded when his car came under fire.
Yemeni security forces killed
Zaidi Shia cleric al-Huthi in 2004
The government announced last September that the army had killed Husain al-Huthi, a preacher from the minority Zaidi community, nearly three months after he started a rebellion in the mountainous northwest.
The uprising, near the border with Saudi Arabia, triggered clashes which left more than 400 people dead.
The Zaidis are a moderate Shia Muslim sect dominant in northwest Yemen but in the minority in the mainly Sunni country.
Authorities had accused al-Huthi of seeking to foment sectarian strife, but he told reporters last July the conflict was a result of his anti-US stand.