US President Joe Biden’s administration imposed sanctions on Yemen’s Houthi rebels on Thursday as officials voiced frustration over the Iran-backed insurgents’ continuing military campaign.

The US also removed sanctions on several former Iranian officials, saying it was acknowledging their changes in behavior.

Sanctions have been imposed by the Treasury Department on several people, including Said Al Jamal, a Houthi supporter who has reportedly run a smuggling network out of Iran, selling oil to benefit the rebels.

US Secretary of State Antony Blinken said the department was hoping to put pressure on the rebels to end their offensive launched in February on the city of Marib, the last significant pocket of government-held territory in the north.

“It is time for the Houthis to accept a ceasefire and for all parties to resume political talks,” Blinken said.

“US will continue putting pressure on Houthis, including through targeted sanctions, to advance those goals.”

In one of its first actions in office, the Biden administration removed a last-minute move by former president Donald Trump to designate the Houthis as a terrorist movement.

Trump moved after aid groups expressed fears that they would have to pull out of Yemen because they were obliged to deal with the Houthis.

The Biden administration has increased diplomatic efforts to address the humanitarian crisis in Yemen.

Biden is also looking to re-enter a nuclear accord with Iran from which Mr Trump withdrew in 2018.

Indirect talks in Vienna have been delayed by Iran’s insistence on a complete removal of sanctions.

The Treasury Department said it would remove sanctions on three former Iranian officials, including former National Iranian Oil Company chief Ahmad Qalebani.