At least nine people have been killed and many others wounded in clashes that erupted between Houthi fighters and tribesmen in a village just north of Radaa city in central Yemen.
Saturday's fighting, in which five Houthis and four tribesmen were killed in Dar Al-Najd, comes as thousands of Yemenis took to the streets of Sanaa to protest against the Houthi group's control of the capital, two days after President Abd-Rabbu Mansour Hadi's resignation left the country in political limbo.
The demonstration on Saturday came as regions in the formerly independent south stepped up their defiance after the Shia Houthi fighters, who hail from Yemen's northern highlands, tightened their grip on Sanaa.
Witnesses said up to 10,000 people marched from Sanaa University towards Hadi's home and back, repeating chants denouncing both the Houthi group and predominantly Sunni al-Qaeda.
"Down, down with the Houthis' rule," chanted protesters who rallied following a call by the Rejection Movement - a group recently formed in provincial areas to challenge the Houthi group.
Women and children joined young men on the streets, waving signs that called for "a real government" and burning portraits of the Houthi leader Abdulmalek al-Huthi.
Protests also erupted in the cities of Taiz, Ibb and Hodeida, organisers said.
Hadi, a key US ally in the fight against al-Qaeda, tendered his resignation along with Prime Minister Khalid Bahah on Thursday, saying he could no longer stay in office as the country was in "total deadlock".
An emergency session of parliament initially scheduled for Sunday to discuss Hadi's resignation has been postponed until "another date to be set later".
Under the constitution, parliamentary speaker Yahya al-Ra'i will take office for an interim period while new elections are organised.
Severing ties with Sanaa
Earllier, leaders from Yemen's Hadramout region said they would reject all orders from the capital while the offices of the president and prime minister remain empty.
The governor and other senior officials in the vast southeastern region told Al Jazeera on Saturday that they decided to sever ties with Sanaa after Hadi and Bahah tendered their resignation.
An Al Jazeera correspondent in Aden said that the Southern Movement, a group which outrightly rejected rule by the Houthis, deployed its fighters to protect the port city from possible attack.
The group, which demands a return to the full independence of the southern region enjoyed from 1967 to 1990, had earlier raised the former flag of South Yemen over Aden's airport and a security headquarters building.
The fall of Hadi's Western-backed government raise fears of chaos engulfing Yemen, strategically located next to oil giant Saudi Arabia and on the key shipping route from the Suez Canal to the Gulf.
Source: Al Jazeera and agencies