Yemen's Huthi rebels on Saturday called the US move to delist the group as a terrorist organisation an "advanced step towards peace".

A US State Department spokesperson said Friday they had "formally notified Congress" of Secretary of State Antony Blinken's intent to revoke the terrorist designation announced in the final days of the Trump administration.

The decision removes a block humanitarian groups said jeopardised crucial aid.

Abdulelah Hajar, adviser to the head of the supreme political council, a Huthi executive body, told AFP that "cancelling the designation is an advanced step towards peace".

The announcement came a day after President Joe Biden announced an end to US support for Saudi-led offensive operations in Yemen.

Hajar said the new US administration had "got off to a good start", but warned the credibility of the steps "will not be achieved unless they are proven on the ground and felt by the Yemeni people -- by lifting the siege and stopping the war".

He also said the newly appointed US special envoy to Yemen, Timothy Lenderking, must "meet all parties", warning that if the Huthis are excluded, "there will be no step towards peace".

The grinding six-year war in Yemen has killed tens of thousands of people and displaced millions, triggering what the United Nations calls the world's worst humanitarian disaster.

Aid groups say they have no choice but to deal with the Huthis, who are the de facto government in much of Yemen, and that the terrorist designation would put them at risk of prosecution in the United States.

The US state department spokesperson said Friday the decision to remove the designation "has nothing to do with our view of the Huthis and their reprehensible conduct, including attacks against civilians and the kidnapping of American citizens". 

"Our action is due entirely to the humanitarian consequences of this last-minute designation from the prior administration."

In ending support for the Saudi-led offensive in Yemen, where 80 percent of the population has been reduced to surviving on aid, Biden was fulfilling a campaign promise to activists who have sounded the alarm over the Yemeni people's suffering.

The state department spokesperson added the US remained committed to helping Saudi Arabia defend its territory against attacks by the rebels.

The kingdom has led a military intervention against the Huthis since 2015.