DUBAI, United Arab Emirates -- Saudi Arabia on Monday announced $1.5 billion in new aid for Yemen, where nearly three years of conflict have devastated the local economy and pushed millions to the brink of famine, causing what the United Nations describes as the world's worst humanitarian crisis.

The kingdom said Monday the coalition it heads in Yemen would also "lead the expansion of additional Yemeni ports" to receive cargo and humanitarian assistance, ensure multiple daily flights of cargo planes carrying aid from Saudi Arabia to Yemen's Marib province, and establish "safe passage corridors" to ensure transportation of aid to non-governmental organizations operating inside Yemen.

The expansion of ports will be supported with up to $40 million from the Saudi-led coalition. The coalition said that it would also allocate up to $30 million to cover transportation costs of non-humanitarian shipments intended for the port of Hodeida, in rebel-held territory, to "their intended destination in Yemen."

Additionally, the kingdom will make a donation of up to $2 billion in fuel for the transportation of humanitarian aid.

The announcement comes amid mounting international criticism of the Saudi-led coalition's role in the war, particularly civilian deaths caused by airstrikes as well as coalition control of Yemen's ports, which are a lifeline for imports.

Human Rights Watch says the Saudi-led coalition delayed and diverted tankers bringing badly needed fuel for power generators for hospitals in 2017, while the rebels the coalition is fighting have also blocked and confiscated aid. Yemen imports about 90 per cent of the country's staple food and nearly all of its fuel and medicine, according to the UN.

"Yes, it's nice the Saudis are sending humanitarian aid to Yemen. Now stop bombing and starving Yemeni civilians," Human Rights Watch's Executive Director Kenneth Roth wrote on Twitter about the new Saudi aid efforts.

Since March 2015, Saudi Arabia has been leading a coalition of nine Arab countries in airstrikes against Yemeni rebels and their allies, who overran Yemen's capital and forced the government into exile. The rebels, known Houthis, who are backed by Iran, still control the capital, Sanaa, and territory in Yemen's north, which borders Saudi Arabia.

Saudi Arabia and its embassies abroad have been keen to promote the country's recent humanitarian efforts in Yemen, including a deposit of $2 billion in Yemen's central bank last week following an urgent appeal. Yemen's currency slid further against the dollar late last year after the coalition blocked access to all of Yemen's ports for several weeks in response to a Houthi missile launched at the Saudi capital.

In opening remarks Monday to reporters ahead of a coalition meeting, Saudi Foreign Minister Adel al-Jubeir laid blame squarely on the Houthis.

"The Houthis are responsible for the destruction and devastation in Yemen," he said, accusing Iran of supplying the rebels with more than 60 ballistic missiles that have been fired at the kingdom. Iran denies it has armed the rebels.

The war has killed more than 10,000 people and displaced 2 million. The Office of the High Commissioner for Human Rights reported last year that airstrikes remained the single largest cause of civilian casualties.

The United Nations says more than 22 million people are in need of humanitarian assistance and 8 million are on the brink of famine.

The Trump administration has expressed concern about conditions in Yemen and has called on Saudi Arabia to allow the free flow of humanitarian aid, fuel and goods at Yemeni ports. The U.S. supports the coalition with refuelling , logistics and intelligence. The U.S. is also a major arms supplier to Saudi Arabia and other members of the coalition.

Germany on Friday said it will not approve arms exports to countries involved in the conflict. Norway has suspended munitions exports to the United Arab Emirates based on its role in the Yemen conflict.

Aid groups that say coalition airstrikes are destroying critical infrastructure and that the coalition needs to do more to facilitate the delivery of staple goods at Yemen's ports. Yemen was already the Arab world's poorest country before the conflict began.

Earlier this month, UN Undersecretary General for Humanitarian Affairs Mark Lowcock called for sustained and higher levels of imports, particularly through ports at Hodeida and Salif, which are in rebel-held territory.

With most of the country lacking access to safe water and sanitation, more than 1 million suspected cases of cholera and more than 2,230 deaths were reported in Yemen last year, according to the World Health Organization. Some 380 cases of suspected diphtheria were also reported, causing at least 38 deaths, almost all among children.

The Saudis have allocated nearly $57 billion for military spending in 2018, or about 22 per cent of the overall government budget for this year. The kingdom, however, has not disclosed how much it spends on the war in Yemen.