Conflict-hit countries have only 3-4 months before millions are at risk of famine, Red Cross says.
Tens of thousands of Yemenis have rallied in the capital, Sanaa, to mark the second anniversary of a war between a Saudi-led military coalition and rebels who had overthrown the government.
The conflict has claimed the lives of more than 10,000 people and pushed the impoverished country to the brink of famine , according to the United Nations.
The gathering on Sunday, which was organised by Houthi rebels, was the biggest event since an Arab coalition led by Saudi Arabia entered the conflict in March 2015 to try to restore the internationally recognised government of President Abd Rabbu Mansour Hadi to power.
Witnesses said that a crowd estimated at more than 100,000 people comprising supporters of the Houthis and former President Ali Abdullah Saleh’s General People’s Congress (GPC) party pressed into Sabeen Square in central Sanaa.
Many waved the red, white and black national colours and chanted against an air campaign targeting the rebels.
Saleh al-Samad, chairman of a governing ruling council that comprises members of the Houthis and Saleh’s GPC, told the crowds that “the battle is still fierce and the war will not end without a victory for the truth and justice”.
Ex-president Saleh, who had rarely been seen in public since he was forced to step down following months of protests in 2011 against his 30 years in office, made a brief appearance to cheers from supporters as the crowd began to disperse.
Hadi was removed after Houthi forces took control of Sanaa in September 2014.
His forces have regained territory since the intervention began, but the rebels still control Sanaa and ports on the southern coast.
The UN estimates that more than 10,000 people, including nearly 5,000 civilians, have been killed in the fighting, and some 40,000 people have been wounded.
The war has also left the country on the brink of a famine, with millions of people displaced, and an estimated seven million people going hungry , according to a UN report.
In Sanaa, Emma O’Leary of the Norwegian Refugee Council, told Al Jazeera that the needs of the civilians are “enormous” and “difficult to describe”.
“We are doing our best to respond to the crisis, but the reality is that this is an extremely difficult environment for all of us,” O’Leary said.
“Security issues, such as the air strikes and the ground fighting, as well as bureaucratic constraints” are a real concern, and that the warring parties must return to the negotiating table, she said.
The Houthis and the GPC are demanding an agreement on a new administration comprising all parties to run the country until new elections, while Hadi supporters say that the Houthis must hand over their weapons and quit the cities they have seized since 2014.
Baraa Shiban, Yemen project coordinator for the UK-based human rights group Reprieve, said the conflict showed no signs of ending.
“We have a situation where the Yemeni government has managed to gain some territory … but that doesn’t mean we’re in any way or form close to the end of the conflict,” he told Al Jazeera.
“We’re looking maybe at a situation of stalemate, where actually no one is able to totally defeat one another – it looks like the humanitarian situation will only deteriorate even further and we have a peace process that is collapsing day by day.”