Doha: Yemeni army units backed by an Arab coalition attacked positions held by Al Houthi rebels in a strategic province east of the capital on Wednesday, a day after a UN envoy delivered a peace proposal to the Iran-allied fighters that control Sana’a.

A three-day ceasefire aimed at paving the way for a political settlement to Yemen’s turmoil collapsed this week, and renewed fighting is threatening UN efforts to end the 19-month-old war.

A Saudi-led coalition launched an offensive in March last year aimed at restoring exiled president Abd Rabbo Mansour Hadi to power and ousting the Iran-allied Al Houthis from their strongholds.

Yemeni forces fired artillery and dislodged Al Houthi fighters from towns in Marib province east of Sana’a on Wednesday, said Saudi state news agency SPA.

The Al Houthi group, who have controlled much of the north of the country since they ousted Hadi in 2015, said jets hit an ice factory near the port city of Mokha and houses and farms in the Serwah district of Marib on Tuesday night.

Capturing Marib is important for the Saudi-led Arab coalition which aims to counter the influence of Iran.

The loyalties of the province are divided. Most of its well-armed clans are allies of the Gulf states. But Al Houthis, mostly members of Yemen’s Zaydi sect, and army units loyal to former president Ali Abdullah Saleh also have friends there.

Al Houthis’ leader, Abdul Malek Al Houthi, made an impassioned speech broadcast live on social media and Lebanon’s Hezbollah-run Al Manar TV station.

He renewed a call for Al Houthis and their allies to complete the formation of a government.

UN special envoy Esmail Ould Shaikh Ahmad visited Sana’a and presented Al Houthis and their allies, the party of Saleh, with a road map addressing “security and political arrangements”, the United Nations said on Tuesday, calling on both sides to extend the ceasefire and allow humanitarian aid into the country. Al Houthis said they would study the proposals.

Rajeh Badi, a spokesman for Hadi’s government, said that any peace proposal must conform to previous plans for Yemen’s political future — a 2011 Gulf initiative which eased Saleh from power, a 2014 national dialogue conference among political factions and a 2015 UN Security Council resolution calling for Al Houthis to disarm and quit major cities.

“Any vision must conform to the three references,” Badi said. “The government has not received any plan from the UN

envoy or the UN yet.”