(updated on Oct 11 to include further delay to UN aid convoy, paragraph 13+14)

LONDON (AlertNet) - United Nations humanitarian officials have appealed for more aid for an estimated 150,000 civilians forced from their homes in northern Yemen by fighting between rebels and the military and voiced alarm over the dire conditions they have to endure.

U.N. humanitarian chief John Holmes also called for greater access to displaced people and urged donors to respond quickly to an emergency plea for $23.5 million in aid.

"Tens of thousands of people have been displaced by the latest wave of fighting in northern Yemen alone, and the number is growing daily," Holmes said at the start of a three-day visit to Yemen this week.

"The people who have fled to the camps have few or no safety nets or coping mechanisms," Holmes said in a statement. "Many came from conditions of great poverty, and have now lost the little that they had, so we need to help them with everything from shelter to food to clean water."

The thousands of displaced people who have chosen to live out of the camps also need help, he said: "There are still many we cannot reach as well as we would like, and our resources are finite."

The U.N. says some 150,000 people have been displaced in northern Yemen in the past five years, including 55,000 since August when the military started its latest campaign to battle a renewed Shi'ite revolt.

Aid agencies are warning of a humanitarian crisis in the north, where people have fled their homes since Shi'ite tribesmen launched an insurgency in 2004. But limited access means aid agencies have no clear idea how many have fled their homes.

Holmes, who visited Haradh in the northwestern province of Hajjah on Friday to inspect one of five camps sheltering displaced, said in a statement that aid agencies needed "better access and the support of the international community if they are going to overcome the challenges that they face on the ground."

MORE AID NEEDED URGENTLY

Holmes said that the U.N. had only received $3.8 million since September 2 in response to a call for emergency funds of $23.5 million to help Yemen's displaced.

"The money is simply not coming in fast enough to meet the requirements. I urge donors to come forward with increased contributions," Holmes added.

Britain voiced concern at the worsening security situation in northern Yemen on Friday and said it would provide 2 million pounds ($3.2 million) to the appeal to help people displaced by the conflict.

Yemeni security forces, meanwhile, said on Saturday they had killed 100 rebels and injured a further 280 in the country's northern Saada province. The conflict has intensified since the army began "Operation Scorched Earth" on Aug. 11.

Much-needed aid due to be dispatched from Saudi Arabia to help some 2,000 people stranded near the border was delayed for another day on Saturday, a U.N. official said.

U.N. staff in southern Saudi Arabia loaded three large trucks with 200 tents, as well as blankets and mattresses, to hand over to a Yemeni aid organisation but the convoy was held up at nightfall at the small crossing point of Alb.

The aid had already been delayed earlier this week while officials from the U.N. refugee agency (UNHCR) sought security clearances from all sides.

Every day scores of Yemeni civilians straggle into the scorching, sandblown Al-Mazraq camp near the Saudi border, fleeing raging battles.

Andrew Knight, a spokesman for UNHCR, said on Friday 20 to 30 families a day were arriving in al-Mazraq camp, which already houses about 6,000 people.

The International Committee of the Red Cross (ICRC) said the conflict was increasingly putting civilian lives at risk, leaving tens of thousands without vital aid and forcing many more to flee. It urged free passage for relief goods.

Yemen, the Arab world's poorest country, twice announced ceasefires in September but they lasted only a few hours. The two sides accuse each other of not allowing the opening of humanitarian corridors.

The media has been restricted in its access to the warzone, where the death toll from the offensive is believed to run into the hundreds.

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