Senior U.S. officials have held a first direct meeting with officials from the Iran-aligned Houthi movement that controls Yemen's capital, two sources familiar with the matter said, as the new U.S. administration pushes to end a six-year war.

The discussions, which have not been officially made public by either side, took place in the Omani capital Muscat on Feb. 26 between U.S. Yemen envoy Timothy Lenderking and the Houthis' chief negotiator Mohammed Abdusalam, the sources said.

The Houthis captured Yemen's capital in 2014 and control most populated areas. A Saudi-led coalition has battled them with tacit Western support since 2015 in a war that has killed tens of thousands and created what the United Nations considers the world's biggest humanitarian crisis.

The Saudis and Houthis have been negotiating for more than a year towards a truce, directly and under the auspices of the United Nations.

The Muscat meeting, one of the sources said, was part of a new "carrot and stick" approach by U.S. President Joe Biden, who last month declared a halt to U.S. support for the Saudi-led military campaign. Biden has also reversed a decision by his predecessor Donald Trump to designate the Houthis terrorists.

The U.S. Treasury Department on Tuesday imposed new sanctions on two Houthi military leaders, accusing them of procuring weapons from Iran and organising attacks, after the group stepped up attacks on Saudi Arabia and intensified an offensive on the ground in Yemen's Marib.

Lenderking met Abdusalam in Muscat after meeting with Saudi and U.N. officials in Riyadh. He also visited the United Arab Emirates, Kuwait and Qatar during his regional tour. The UAE in particular has played a major role in the Saudi-led campaign in Yemen.

The sources said Lenderking had pressed the Houthis to halt the Marib offensive and encouraged the movement to engage actively with Riyadh in virtual talks on a ceasefire.

Abdulsalam, who is also the spokesman of the Houthi movement, did not respond to a Reuters' requests for comment.

A U.S. State Department spokesperson said Lenderking has been meeting with regional senior government officials and has met with U.N. special envoy Martin Griffiths during his trip.

"We will not be commenting on all his engagements," the spokesperson told Reuters.

CEASEFIRE TALKS

In ceasefire talks, Saudi Arabia has been seeking assurances on border security and curbing the influence of regional arch-rival Iran. The Saudi level of representation at virtual talks was recently raised, with Riyadh's ambassador to Yemen, Mohammed al-Jaber, now speaking with Abdulsalam, the sources said.

Jaber did not respond to a request for comment.

Riyadh wants a buffer zone inside Yemen along the border. The Houthis want an end to blockades on the Red Sea port of Hodeidah and Sanaa airport.

If agreement is reached, one of the sources said, it would be taken to U.N. envoy Griffiths to prepare for broader peace talks that would include Yemen's internationally recognised, Saudi-backed government, now based in the port of Aden.

The war, stalemated for years, has shifted to the gas-producing region of Marib where hundreds of fighters have been killed in a Houthi offensive, the most deadly clashes since 2018.

On Wednesday, heavy clashes were reported around Marib and in Taiz, another heavily disputed city.