Houthi militias ride on the back of a patrol truck as they secure the site of a gathering held by tribesmen loyal to the Houthi movement, in Yemen’s capital Sanaa December 14, 2015.

U.S. President Barack Obama called on Yemen’s warring parties to respect a ceasefire that lay in tatters Friday, amid fighting between government and rebel forces.

The White House said that Obama, in a call with Abu Dhabi’s crown prince, stressed the “urgent need for all parties to adhere to the ceasefire in Yemen” and to seek a diplomatic solution to the conflict.

A Saudi-led coalition launched an air war against the Houthi militias and their allies in March.

The United Nations Special Envoy for Yemen also voiced deep concern on Friday, the fourth day of peace talks, at “numerous reports of violations of the cessation of hostilities” and set up a mechanism to strengthen compliance, a U.N. statement said.

Ismail Ould Cheikh Ahmed said that the heads of delegations at talks being held in Switzerland between the exiled Yemeni government and Houthi militias had renewed their commitment to a ceasefire that took effect on Tuesday.

“He urges all parties to respect this agreement and allow unhindered access for the delivery of humanitarian assistance to the most affected districts of Yemen,” the statement said. Talks would continue on Saturday to “build on what was agreed upon in previous days and continue efforts to find an urgent political resolution to the crisis in Yemen”.

Related articles across the web

• White House Urges Muslims to Counter Extremist Message
• Barack Obama's cute moments with kids
• Obama signs education reform bill into law
• President Obama to Visit San Bernardino, Meet With Families of Victims
• The Obamas celebrating Christmas through the years
• Barack Obama Plans to Support Mexican Minors Trying to Cross the U.S. Border
• White House: No idea why Americans are buying so many guns
• President Obama to hold year-end news conference