WASHINGTON (Reuters) - U.S. Secretary of State Mike Pompeo said on Wednesday that he certified to Congress that Saudi Arabia and the United Arab Emirates were working to reduce civilian casualties in Yemen, avoiding a limitation on U.S. help for its ally Saudi Arabia.

FILE PHOTO: U.S. Secretary of State Mike Pompeo waves to the media before his meeting with Egyptian Foreign Minister Sameh Shoukry at the State Department in Washington, U.S., August 8, 2018. REUTERS/Yuri Gripas/File Photo

Without the certification, U.S. tanker aircraft would have been restricted in the refueling of Saudi-led coalition aircraft conducting strikes against Houthi rebels backed by Iran.

Pompeo’s decision drew the derision of critics of the Saudi-led air campaign, which has long been denounced even by Western allies for the number of civilian casualties it has caused and for driving Yemen to the brink of famine.

The three-year-old war in Yemen, widely seen as a proxy battle between regional rivals Saudi Arabia and Iran, has killed more than 10,000 people.

Pompeo said in a statement he advised Congress on Tuesday that “the governments of Saudi Arabia and United Arab Emirates are undertaking demonstrable actions to reduce the risk of harm to civilians and civilian infrastructure resulting from military operations of these governments.”

A number of factors underpinned Pompeo’s decision, including the Saudi-led coalition’s admission of blame and agreement to compensate the victims of an Aug. 9 air strike on a bus that killed dozens of people, including 40 children, a State Department official said.

The coalition also has pledged to hold accountable those responsible for the air strike, while Saudi Arabia and the UAE have continued supporting U.N. efforts to find a political settlement to the conflict, said the official, who requested anonymity.

But some lawmakers on both sides of the aisle pushed back.

“Pompeo’s ‘certification’ is a farce. The Saudis deliberately bombed a bus full of children. There is only one moral answer, and that is to end our support for their intervention in Yemen,” Democratic U.S. Representative Ro Khanna said in a post on Twitter.

Republican Representative Justin Amash said the United States should stop selling weapons and providing military assistance to Saudi Arabia.

“This war in Yemen is unconscionable, and the United States should not be a party to it,” Amash said on Twitter.

U.S. lawmakers, concerned about a growing humanitarian disaster in Yemen, required Pompeo to certify by Wednesday that the Saudis and the UAE were taking meaningful measures to reduce civilian casualties and allow humanitarian aid deliveries.

Without the move by Pompeo, U.S. aircraft would have been barred from refueling Saudi-led coalition aircraft in mid-air except when they were striking Yemeni factions of al Qaeda and Islamic State, the Houthis’ use of ballistic missiles, or protecting U.S. military units and international commercial shipping.

Larry Lewis, a former State Department adviser to Saudi Arabia on reducing civilian casualties, called Pompeo’s statement “objectively false.”

“There’s more that can be done,” Lewis, now the director of the Center for Autonomy and Artificial Intelligence at the CNA, a Washington think tank, wrote in an email. “Whether the U.S. government is willing to do more is another matter.”

U.S. Defense Secretary Jim Mattis said he backed Pompeo’s finding.

Saudi Arabia is leading a Western-backed alliance of Sunni Muslim Arab states to try to restore the internationally recognized government of Yemeni President Abd-Rabbu Mansour Hadi, ousted from the capital Sanaa by the Iran-aligned Houthis in 2015.

An attempt to convene U.N.-mediated peace talks in Geneva collapsed last weekend after the Houthi delegation failed to show up for three days.

The United States and other Western powers provide arms and intelligence to the alliance. Human rights groups have criticized them over coalition air strikes that have killed hundreds of civilians at hospitals, schools and markets.

The Pentagon believes that its assistance, which includes refueling coalition jets and training in targeting, helps reduce civilian casualties.