Airstrikes and ground combat in Yemen killed an estimated 176 fighters and civilians on Monday, local residents and media said. The incident marked a major spike in fatalities that, if confirmed, would be the highest single-day death toll since the Arab-led coalition began its bombing campaign in March, Reuters reported.

The news comes as the Saudi-led coalition stepped up its air campaign against the Shiite Houthi rebels that control large swaths of the country. The U.S.-supported coalition has repeatedly drawn criticism from international bodies that call for a humanitarian truce. A group of regional and tribal militia allied to the exiled government also clashed with the Houthis on the ground.

The Houthi-run Saba news agency, as cited by Reuters, said that 54 people were killed in raids north of the capital Sanaa, including a number of women and children. Another 40 people were reportedly killed in a raid on a livestock market in the town of al-Foyoush in the country’s south, and 30 died in an attack on a Houthi checkpoint near the port city of Aden.

The situation in Yemen has been declared a “catastrophe” by United Nations Secretary General Ban Ki-moon, who has called for a humanitarian ceasefire to allow the transportation of food and aid into the country. Activists and aid groups have warned of increasing shortages of food, electricity and medicine as the country’s infrastructure remains battered under the ongoing conflict.

U.N. special envoy to Yemen Ismail Ould Cheikh Ahmed has been in talks with Houthi officials to secure a ceasefire agreement. Representatives from the exiled government of President Abed Rabbo Mansour Hadi in Riyadh said that they were still holding consultations on implementing an April U.N. resolution that called for an immediate Houthi withdrawal from all occupied cities and delivery of aid supplies.

"We are now in consultations for guarantees to ensure the success of the truce," Hadi spokesman Rajeh Badi told Reuters.

"The mechanism we presented to implement (the U.N. resolution) demanded real guarantees to ensure aid is delivered to those who need it," he said, noting that talks were underway to "lift the deliberate siege on Aden, Taiz, Lahj and Dhalea."

A previous ceasefire was declared in May, during which supplies and medicine were delivered to the stricken country, but the death toll has now spiraled to over 2,800 as the conflict drags on.

Aid group Doctors Without Borders (MSF) said on Monday that medical facilities across the country had taken in hundreds of people who were wounded in the bombings or shellings in recent weeks. "It is unacceptable that airstrikes take place in highly concentrated civilian areas where people are gathering and going about their daily lives, especially at a time such as Ramadan," MSF Yemen mission head Colette Gadenne said in a statement.