The U.N. is expected to add Yemen to the list of the world’s worst humanitarian crises, raising the pressure on the Saudi government to halt a deadly military campaign and blockade. The news comes as aid officials warn parts of Yemen are on the brink of famine amid internal fighting and a continued Saudi-led air campaign. U.N. aid chief Stephen O’Brien says 80 percent of Yemen’s 25 million people need aid and the health system faces “imminent collapse.” The warning comes days after ceasefire talks between Yemen’s warring factions broke down in Geneva. At the Security Council, U.N. special envoy Ismail Ahmed renewed calls for a humanitarian truce.

Ismail Ahmed: “Both sides showed signs of constructive engagement. There is an emerging common ground upon which we can build to achieve an eventual ceasefire coupled with a withdrawal of combatants. While we pursue a sustainable longtime cessation of violence, I call on all the relevant parties to agree without delay to a humanitarian truce, especially during the holy month of Ramadan. We should not forget that Yemeni are living under dire conditions, and it pains me to witness this ongoing suffering.”

In some of Yemen’s latest violence, 17 civilians were reportedly killed and dozens wounded today when Houthi rebels fired on the southern port city of Aden. More than 1,000 prisoners, including al-Qaeda members, also escaped a prison in the city of Taiz amid clashes between rival forces.