The United Nations refugee agency says a humanitarian crisis is unfolding in Saada city in northern Yemen. The UNHCR and other aid agencies are repeating their call for the opening of humanitarian corridors so they can assist thousands of people who are trapped inside the city because of fierce fighting between al-Houthi forces and the government.

They say the situation in Saada continues to worsen and they are gravely concerned about the fate and well-being of civilians.

The fighting is now entering its third week and it is taking a heavy toll. U.N. refugee spokesman, Andrej Mahecic, says more than 35,000 people have been displaced in and around Saada since fighting resumed.

He says an estimated 150,000 internally displaced people have been affected by the fighting since 2004. "According to those who managed to flee the besieged city and our staff on the ground, the fighting appears to be concentrated in the old Saada city. They also report frequent air strikes. As a result, more people are fleeing to the other parts of the Saada city seeking shelter and assistance-placing an additional burden on neighbors, friends and relatives as their own meager resources are running out. A 12-hour curfew is still in force restricting the movement of the local population and the internally displaced people especially during the night. Food reserves are running out and black market prices have risen dramatically in most of the districts affected by the fighting," he said.

Mahecic says those who can afford to pay are smuggled out of Saada city across the mountains to a neighboring province. He says UNHCR local partners have managed to register 2,200 IDP families in Saada city and nearby villages, despite the ongoing fighting.

But, he adds, the security situation continues to hamper the distribution of relief items to vulnerable families. With the worsening of the situation in the north, the opening of humanitarian corridors in northern Yemen that would allow civilians to leave the conflict zone and humanitarian workers to deliver much needed humanitarian aid to thousands of displaced people in this remote part of the country is a top priority for UNHCR," he said.

Mahecic says the UNHCR urgently needs $5 million to respond to the emergency. He appeals to the generosity of the international community and the Muslim world in particular to alleviate the suffering of the Yemenis during this holy month of Ramadan.