Shia armed fighters captured a town south of the Yemeni capital of Sanaa early on Sunday, after blowing up the home of a rival politician, security officials said.
In Sanaa, the rebels, known as the Houthis, stormed the headquarters of the capital's local government. According to officials, the rebels chased out the governor, Abdul-Ghani Jameel, who they accuse of corruption.
The Yemeni officials spoke on condition of anonymity because they were not authorized to speak to the media.
Sunday's developments reflected the growing strength of the Houthis, who overran Sanaa last month and captured a key Red Sea port city last week along with a province south of the capital.
Early on Sunday, the Houthis captured the town of Yarim about 106 miles south of Sanaa, in the province of Ibb. Yarim has a population of more than 100,000 and lies along the main road to Yemen's southern provinces.
The Houthis took over the house of a prominent Islamist politician in Yarim on Saturday, setting off clashes that left 12 people dead. The politician, who comes from the powerful Islah or Reform Party, was not home at the time. On Sunday, according to the officials, the Houthi rebels blew up the house.
The Houthis are at sharp odds with the Islah Party and powerful Sunni tribes allied with it. The rebels say they are demanding a bigger share of power and a change to the country's political order following the 2011 protests that forced longtime leader Ali Abdullah Saleh out of office. But their military advances suggest they are seeking to take full control of Yemen's northern provinces at a time when secessionist sentiments are growing in the once-independent south of Yemen.
Some Yemenis tell Al Jazeera there is a hidden alliance between the Houthis and former president Ali Abdullah Saleh, a Zaidi Shia Muslim who stepped down in 2012. Without the backing of Saleh, they say, the Houthis would not have been able to take the capital and other parts of the country.
Predominantly Shia Iran’s administration voiced support for the Houthis voiced support for the group late Saturday.
Ali Akbar Velayati, a spokesman for Iran's Supreme leader Ayatollah Ali Khamenei, said in a meeting with a group of Yemeni clerics in Tehran that "the Islamic Republic of Iran supports the rightful struggles of [the Houthis] in Yemen, and considers the movement part of the successful Islamic Awakening.”
Many in Yemen have also told Al Jazeera that the battle between the Houthis and Yemeni government is a proxy war between Iran and Sunni-majority Saudi Arabia, who are expected to be angered by Tehran's comments.
On Sunday, thousands in the Houthi-controlled port of Hodeida demonstrated to demand that the rebels leave the city. Similar protests had taken place in Sanaa in recent weeks. In Yarim and in Ibb, where the Houthis have some military presence but are not in full control of the city, local authorities closed all schools on Sunday because of the tense security situation.
Yemen has been beset for years by an Al-Qaeda-led insurgency that has staged dozens of suicide attacks against military and security personnel. It also has endured crushing poverty that has bred resentment — and outright rebellion — that contributed to a secessionist movement in its southern region.
The advances by the anti-American Shia rebels take advantage of the disarray in Yemen's army and security forces. Yemen is one of the most active battlegrounds in the U.S. campaign against Al-Qaeda’s leaders, hideouts and camps, and American drones operate openly there with permission from the Yemeni government.
Al Jazeera and The Associated Press