22 international relief organizations operating in Yemen have called on the administration of US President Joe Biden to return to Washington's designation of the Houthi group as a terrorist organization, warning that millions of Yemenis are at risk.

The organizations, including "Oxfam, the Norwegian Refugee Council," said that the classification came "at a time when famine is a real threat to a country devastated by 6 years of conflict, and it must be canceled immediately."

Anthony Blinken - who was chosen by the US President to take over the State Department - pledged Tuesday to "immediately reconsider" the decision of his predecessor, Mike Pompeo, to designate the Houthis a "terrorist organization."

This designation freezes any Houthi assets linked to Washington, prevents Americans from doing business with them, and criminalizes providing support or resources to their group.

The decision - which prohibits direct dealings with the "Ansar Allah" group, the political arm of the Houthi group - entered into force on January 19, but the administration of outgoing President Donald Trump was quick to announce exemptions.

For its part, the US Treasury said in a statement that these exemptions include the activities of certain organizations, including the United Nations, the International Committee of the Red Cross and non-governmental organizations that support "humanitarian projects."

It also includes certain transactions related to the export or re-export of agricultural goods, medicines, medical devices, spare parts and components for medical devices, or software updates for medical devices to Yemen.

But these organizations considered that even with the licenses and exemptions in place for humanitarian work, "the classification will have serious implications, causing delays and uncertainty in our ability to provide assistance."

While Saudi Arabia and the Yemeni government welcomed Washington's decision, prominent American lawmakers called for a quick reversal of the step, at a time when senior UN officials warned of famine if the decision was implemented.

The Houthis have controlled the capital, Sanaa, and large areas of Yemen since 2014, and have been fighting daily battles against forces loyal to the internationally recognized authority backed by a Saudi-led military coalition since March 2015.

This conflict left tens of thousands of people dead and pushed about 80% of the population to rely on humanitarian relief, amid the worst global humanitarian crisis, according to the United Nations.

The war also displaced some 3.3 million people and left an entire country on the brink of famine.