A new round of UN-sponsored talks over a prisoner swap deal between the Yemen's government and the Houthi rebel group was postponed due to Washington's designation of the rebels as "terrorists," an official said on Sunday.

According to local Yemeni official, who asked to remain anonymous, "talks about exchanging prisoners between the country's two warring rivals were scheduled to begin this week particularly on Saturday under the auspices of the United Nations in Jordan."

He confirmed that due to the U.S. government's decision to designate Ansar Allah, more commonly known as the Houthi rebel group in Yemen, as "terrorists," the UN-sponsored talks were delayed.

Last week, U.S. Secretary of State Mike Pompeo said that the U.S. Department of State would blacklist the Houthis on Jan. 19, one day before President-elect Joe Biden takes office.

However, the United Nations and Yemeni analysts noted that this move would complicate the UN-brokered peace plan and international aid efforts in the impoverished Arab country.

Yemen has been mired in a civil war since late 2014, when the Iran-backed Houthi rebels seized control of several northern provinces and forced the internationally-recognized government of Hadi out of the capital Sanaa.

The six-year-old war has killed tens of thousands of people, displaced 4 million and pushed Yemen to the brink of starvation.