GENEVA — Saudi Arabia and the United Arab Emirates drew praise Tuesday at a U.N. conference for offering $1 billion in aid for Yemen, where their air campaign against Houthi rebels has killed thousands of civilians and their crippling blockade has hindered aid delivery.

The one-day conference co-hosted by Sweden, Switzerland and the United Nations collected pledges totaling $2.01 billion from 40 countries and organizations.

U.N. Secretary-General Antonio Guterres acknowledged that some donors were also "parties of the conflict."

"We all know who ... the parties to the war (are)," he told reporters. "But the two things need to be seen separately, independently of the fact that there is a war. There are humanitarian obligations that are assumed by countries."

With the situation worsening — Guterres called it "catastrophic" — the conference easily surpassed the funding pledges of $1.1 billion at a similar event last year. Overall, the U.N. has appealed for $2.96 billion to provide assistance and protection to people in Yemen in 2018.

"Several countries have already announced that there will be more donations from now until the end of the year," the U.N. chief said. "So we are quite optimistic."

Guterres added that "as important as the financial contributions to this conference is the commitment of the parties to the conflict to come together to put an end to the war."

He said information gleaned by his new special envoy for Yemen, Martin Griffiths, during a trip to the region led him to believe there were "positive perspectives" that could possibly lead to an "effective intra-Yemeni dialogue" at some point. Guterres cited an "opportunity to be seized."

A Saudi-led, Western-backed coalition has been at war with Iran-allied Shiite rebels known as Houthis for three years in a conflict that has killed more than 10,000 people and left 22.2 million people needing humanitarian aid. The conflict has fanned the world's worst recent cholera outbreak and put many on the brink of starvation. Some 8.4 million people do not know how they will get their next meal, according to U.N. estimates.

Health and sanitation systems are teetering in Yemen. Guterres noted that a child under 5 dies every 10 minutes from preventable causes.

In his prepared remarks, Guterres noted how Saudi Arabia and the United Arab Emirates — who have given military backing to Yemen's government, notably with air power and a sea blockade of rebel areas — had "generously provided" $930 million toward the humanitarian response plan even before the conference began.

The final list of pledges showed that each country had offered $500 million.

The United States announced nearly $87 million in additional humanitarian aid, while the European Union pledged €107.5 million in new funding this year.

Thomas Staal, counselor for the U.S. Agency for International Development, or USAID, said the United States extended its "gratitude" to Saudi Arabia and UAE "for their significant contributions to the United Nations' coordinated response."

Amnesty International said it continues to turn up "grave" violations of international humanitarian law on all sides of the conflict.

"All warring parties must be held accountable," it said in an email. "All countries, including the United States and the United Kingdom, must also halt the flow of all arms to the conflict."

Ken Roth, director of Human Rights Watch, said any humanitarian contribution was welcome amid such severe suffering.

"But that shouldn't absolve or change the subject from the Saudi-led coalition's primary responsibility for Yemen's humanitarian crisis due to its blockade and repeated bombing of Yemeni civilians and critical Yemeni infrastructure," Roth wrote in an email.

"Sending remedial aid doesn't exculpate Saudi Arabia and the UAE for their war-crime strategy of blockading and bombing Yemeni civilians," he added.