At talks in Sweden last month, the UN brokered several agreements between the Shiite Huthi rebels and the Saudi-backed government that had been seen as providing the best opportunity yet of ending nearly four years of devastating conflict.

The Shiite Huthi rebels said they carried out the strike on Al-Anad air base, in government-held Lahij province some 60 kilometres (40 miles) north of Yemen's second city Aden.

At least 12 people were wounded in the attack, including top commanders, according to medics at the Ibn Khaldoun hospital in the provincial capital Houta.

Footage of the attack showed a drone exploding over a podium around which dozens of military personnel were standing.

Soldiers scrambled to carry wounded comrades to military vehicles, while a man holding a camera bled on the ground.

An AFP correspondent at the scene said that journalists were among the wounded.

Originally built by the then Soviet Union during the Cold War, Al-Anad served as the headquarters for US troops overseeing a long-running drone war against Al-Qaeda until March 2014, when it was overrun by the Huthis.

The base was recaptured by government forces in August 2015 as they recovered territory from the rebels across the south with support from a Saudi-led military coalition.

Top brass among wounded

Yemen's deputy chief of staff Saleh al-Zandani, intelligence Brigadier General Saleh Tamah and senior army commander Fadel Hasan were among the wounded, along with Lahij governor Ahmad Abdullah al-Turki, doctors at Ibn Khaldoun hospital told AFP on condition of anonymity.

Chief of staff General Abdullah al-Nakhi was also at the base at the time of the attack, a pro-government official said. He was not named among the casualties.

The attack came one day after UN envoy Martin Griffiths warned "substantial progress" was needed on the ground before full-blown negotiations could be launched on ending the civil war.

The strike on loyalist top brass is likely to create a new obstacle to the launch of formal peace talks.

"Both sides have largely adhered to the ceasefire and there has been a significant decrease in hostilities," Griffiths told the UN Security Council on Wednesday.

In last month's talks, the warring sides agreed truce deals for the key rebel-held aid port of Hodeida and battleground third city Taez.

The breakthrough sparked hopes of ending a conflict which has left nearly 10 million people just one step from famine in what the UN describes as the world's worst humanitarian crisis.

But Griffiths has warned repeatedly that even small steps towards peace remain fragile.

"It is my view and it is shared by the leadership of both parties, but also others, that substantial progress, particularly on Hodeida of course, is something that we would like to see before we reconvene the next consultations," he said.

A new meeting is to be held in the Jordanian capital Amman next week to follow up on a huge prisoner swap agreed by the warring parties last month.

The United Nations is working to schedule a new round of consultations, possibly in Kuwait, aimed at drafting a political framework for an end to the conflict.

The war between the Huthis and loyalist troops escalated in March 2015, when President Abedrabbo Mansour Hadi fled into Saudi exile, prompting the the Saudi-led coalition to intervene.

International pressure for a peace settlement has intensified as the humanitarian crisis has worsened and after Saudi Arabia sparked a Western outcry over the October murder of dissident journalist Jamal Khashoggi inside the kingdom's consulate in Istanbul.

De facto ruler Crown Prince Mohammed bin Salman, who was the architect of the Saudi intervention in Yemen, has been held responsible by the US Senate for ordering the killing.

Secretary of State Mike Pompeo, who is on a whistlestop Middle East tour, is to raise the issue in talks in Riyadh later this week, US officials said.