A top US diplomat on Wednesday denied a claim by Yemen's Houthis that the Biden administration had offered to recognise the Iran-backed rebels in Sanaa if they stopped attacks in the Red Sea and beyond.

Special envoy to Yemen Tim Lenderking also said he had seen “very worrying” evidence that Russia is seeking to arm the Houthis.

A senior Houthi official this week said the US had offered to recognise the Houthis and other unspecified “temptations” for the group to stop attacking shipping in the Red Sea and launching strikes against Israel.

“There is no truth to the story,” Mr Lenderking told The National at an event hosted by the Arab Gulf States Institute in Washington on Wednesday. “It is not the case that the US is offering any inducements to recognise the Houthis is a legitimate government.”

Speaking alongside Yemen's ambassador to Washington, Mohammed Al Hadhrami, he said the US is “working very closely with the legitimate government in Yemen”, which has moved to Aden since the Houthis seized control of the capital Sanaa in a 2014 coup that led to the current civil war.

Mr Al Hadhrami said the Houthis want to turn Yemen into a theocratic state and warned that diplomacy “will not work” with the rebels. He listed a moves short of a full-scale military intervention to increase pressure on the group, including redesignating them as a foreign terrorist organisation, securing Yemen's borders and cutting supply lines for weapons.

Outside Yemen's decade-long civil war, the Houthis have unleashed a campaign against Red Sea shipping, saying say they are attacking ships linked to Israel in solidarity with the Palestinians in Gaza. The group has also fired at least one ballistic missile into Israel and steered at least one attack drone into the country.

The US delisted the Houthis as a foreign terrorist organisation and as specially designated global terrorists in February 2021, as President Joe Biden's administration sought to make it easier to get aid into Yemen, where a humanitarian crisis has pushed millions to the brink of starvation.

But the administration partially backtracked this year, redesignating the Houthis as a specially designated global terrorist group, but not calling them a foreign terrorist organisation, which carries more serious implications. Mr Lenderking said that designation was under consideration.

“We're in very active conversation with the Yemen government, within our own leadership here about the prospect of doing that, whether that's helpful, whether that achieves objectives that we want to see,” he said.

Mr Lenderking said the Houthis' relationship with Russia is growing stronger and has become “extremely troubling”.

“The Russians are very irritated with our strong policy on Ukraine. They're finding other outlets to take it out on us. Yemen is another venue where they have been seeking to arm the Houthis, which would be a game changer.”

Mr Al Hadhrami said, however, that Russia had assured Yemen's Foreign Minister on a recent Moscow visit they were not supplying weapons to the Houthis.

“If we see evidence that this is not the case, I think our position will change,” the ambassador said.

The Houthis on Sunday claimed responsibility for a “hypersonic” ballistic missile attack on central Israel, praising it for causing “fear and panic” throughout the country. They called the missile Palestine 2, which the Pentagon on Tuesday denied had hypersonic capabilities.

Mr Al Hadhrami and Mr Lenderking both said they want to see a ceasefire in Gaza and regard it as key to ending attacks in the Red Sea.

Mr Lenderking said countries and groups with inside knowledge of the issue assure him the Houthis would stop their attacks in the event of a ceasefire.

“Even if they do that, though, they've still demonstrated the capability to menace shipping, and they have the willingness to do it. So the United States is not going to say, OK, game over,” he said.

The Houthis last month struck the MV Sounion oil tanker, threatening the worst oil spill in history. The vessel is now under tow for salvage but Mr Lenderking said it is still on fire.