Two lawmakers said the United Arab Emirates made the promise to address their concerns and that as a result, they would drop their attempt to block $1.2 billion in arms sales to the Gulf power.

Senator Chris Van Hollen, a member of President Joe Biden's Democratic Party, released a letter addressed to him from the White House that described UAE assurances in the relationship with Sudan's Rapid Support Forces.

"Despite reports we have received suggesting the contrary has occurred to date, the UAE has informed the administration that it is not now transferring any weapons to the RSF and will not do so going forward," said the letter signed by Brett McGurk, the White House coordinator on Middle East policy.

In the letter, McGurk promised to offer an assessment on the "credibility and reliability of these assurances" by January 17 -- three days before President Joe Biden hands the White House back over to Donald Trump.

Van Hollen said he had been seeking to use weapons as "leverage" to reduce the "horrific violence" in Sudan.

He warned that he would again attempt to block arms sales if the UAE does not comply with the promise.

Fellow Democrat Sara Jacobs, who led a parallel effort in the House of Representatives, also vowed to "carefully monitor" adherence by the UAE.

"Without the UAE's support, the RSF will not have the same capabilities to wage this war -- making negotiation and a ceasefire a much likelier alternative," she said in a statement.

The UAE embassy in Washington did not immediately respond to a request for comment.

The UAE has repeatedly denied supporting the RSF, whose war with Sudan's army has killed tens of thousands of people and displaced more than 11 million others since April 2023.

Last year, United Nations experts tasked with monitoring an arms embargo on the Darfur region said accusations that the UAE had funnelled weapons to the RSF through Chad were "credible."

The lawmakers had been seeking to hold up a $1.2 billion sale to the UAE that included long-range ATACMS missiles.

Trump has shown a greater willingness on selling weapons and in his last term promised advanced F-35 jets and armed drones as part of a package in which the UAE recognized Israel.

The F-35 purchase languished after Biden defeated Trump in the 2020 election, with the new administration seeking greater oversight of the weapons.