A follower of the Houthi movement holds up a photo showing Yemen’s President Abd Rabbu Mansour Hadi (R) sitting with General Ali Muhssein (L) and General Saleh Fadhil, outside Fadhil’s house.

SANAA — Armed Shi’a rebels pushed into Yemen’s capital Sanaa after clashing with the army on the northwestern outskirts on Thursday, security sources and residents said, causing further instability after weeks of fighting and protests.

Residents of northwest al-Shamlan district said the Houthi gunmen were advancing along Thalatheen Street, a major route into the western edge of Sanaa.

State news agency Saba also reported later Thursday that airlines had suspended flights to Sanaa airport for 24 hours pending the security situation.

One report on Al Jazeera television had said earlier that rebels attacked a military checkpoint near the airport. One official at the Yemeni television building also said the rebels had targeted the facility with missiles on Thursday evening.

The fighting has further destabilized an impoverished country also struggling to overcome a secessionist movement in the south, the spread of an al-Qaeda insurgency and other threats.

A military source said Houthi gunmen had also attacked an army camp on the southern entrance of the capital, but soldiers repelled the assault.

In recent weeks, Houthi protesters have been blocking the main road to Sanaa’s airport and holding sit-ins at ministries calling for the ousting of the government and the restoration of subsidies cut by the state in July as part of economic reforms.

At least 42 people have also been killed in clashes involving Houthi fighters in different parts of the country since Tuesday.

The United Nations’ special envoy to Yemen meet Houthi leader Abdulmalek al-Houthi in Saada province on Wednesday to try and find a way out of the conflict. The three-hour meeting was “constructive and positive” Jamal Benomar was reported as saying.

The Houthis said on Monday they would no longer take part in negotiations with the Yemeni government about their grievances because of what they termed “foreign intervention” in the discussions.