Yemen is "on the verge of total collapse", warns the United Nations, with gunfire and shooting taking a toll on its civilians.

The assessment by the UN high commissioner of the situation in Yemen, as Houthi rebels battle a Saudi-led coalition backing the government, is supported by aid organisations like Médecins Sans Frontières (MSF) and Red Cross.

These groups are calling on all sides to protect civilians and let aid teams help those affected by the fighting.

Dwindling medical supplies and safety of their workers working amidst gunfire and bombing are concerns for the aid groups.

MSF emergency unit manager Teresa Sancristoval expressed concern over widespread violence with bombing in Hudaydah, Haradh, al-Mazraq, Saada, Aden and Dhalea.

Air and sea blockades are making it impossible to send desperately needed assistance to those who needed it.

The International Committee of the Red Cross (ICRC) spokeswoman Marie Claire Feghahli, based in Saana, said hospitals were inundated with the wounded and were struggling to cope.

"The hospitals are just overwhelmed and they are extremely busy treating the injuries that come their way and the counting is just not happening as it should be."

Feghahli told the BBC that vital medical supplies were running low.

The airports are closed and the group failed to obtain all the clearances needed for its plane to come from Amman to Sanaa.

The safety of volunteers is another concern with one Yemen Red Crescent Service (YRCS) volunteer shot dead while evacuating the wounded.

This attack will put significant pressure on humanitarian workers and volunteers working to help the wounded, Feghahli said.

The UN said at least 93 civilians had been killed since the 10-nation coalition, led by Saudi Arabia, launched an air campaign five days ago.

Iraq has witnessed mass protests against the airstrikes led by its largely Shiite groups.

The Saudi coalition is defending the government of Yemen's president Abd Rabbuh Mansur Hadi who has fled the country. Hadi has accused Tehran of trying to exert control over Yemen by backing the Shi'ite rebels, and voiced his support for foreign intervention in the Arab world's poorest nation.

The Arab League has agreed to the creation of a joint Arab military force, consisting of 40,000 troops from Saudi Arabia, Iraq, Jordan, Qatar and Egypt to fight the rebels as well as tackle future security issues in its member nations.

Justifying the air strikes that started on Thursday, Arab League chief, Nabil Elaraby, has said: "Yemen was on the brink of the abyss, requiring effective Arab and international moves after all means of reaching a peaceful resolution had been exhausted to end the Houthi coup and restore legitimacy."

The Saudi-led air campaign will continue until all Houthi militia surrender and make way for a unified Yemen, a spokesman said.