UN Secretary General Ban Ki-moon on Sunday pleaded for the resumption of peace talks in Yemen and called for an end to all military action in the war-torn country.
Ban, speaking in Doha on the sidelines of a UN crime conference, said the fighting in Yemen should not be allowed to grow into a protracted regional conflict.
"There should be a cessation of military moves as soon as possible," said Ban, sitting alongside the Qatari prime minister, Sheikh Abdullah bin Nasser bin Khalifa al-Thani.
"Let the peace process be resumed, the United Nations stands ready."
He added: "We urgently need a deescalation and return to peaceful negotiation. I firmly believe that... negotiations remain the best chance to prevent a long, drawn out conflict."
Ban also warned that the escalation in fighting was leading to a huge humanitarian crisis.
"I am also deeply concerned about the military escalation where civilian casualties are mounting and public infrastructure is being destroyed," he said.
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The UN chief said more than 600 people had been killed and 2,000 injured so far in the fighting.
Saudi-led air strikes continued in Yemen on Sunday.
The Saudis lead a coalition of nine Arab countries, including Qatar, which have carried out air strikes against the Huthi Shiite rebels since March 26.
Qatar has some 10 jets carrying out strikes as part of the operation.
Al-Thani said Gulf countries were compelled to take military action for reasons including the "violation of a number of UN Security Council resolutions" by the rebels.
Ban said he and Al-Thani held a "productive meeting" on Sunday in which they discussed issues in the Middle East, including Iraq and Gaza, as well as crime.
Ban called on Baghdad to maintain the rule of law in areas where Islamic State fighters had been defeated, amid concerns about the actions of militias in the country.