A Yemeni tribal chief said Wednesday that 33 of the 41 people killed in a Saudi-led air strike on a market in a northern province were rebel fighters, not civilians as first reported.

Medics and tribal sources said that the Tuesday strike in the rebel-held Hajja province killed 41 people and wounded 35.

A health official in Hajja said the dead were civilians.

But on Wednesday a tribal chief close to Yemen's Iran-backed Huthi rebels said that 33 of those were "fighters".

"The fighters were riding in three vehicles at a military camp that was hit by three air raids," the chief told AFP on condition of anonymity.

He added that Saudi-led warplanes then hit the market when the Huthis arrived there.

In Riyadh, Brigadier General Ahmed al-Assiri, spokesman for the Saudi-led coalition, said it was "a militia gathering."

In an interview with AFP, he gave no other details of the incident but said the area is a place for buying and selling qat, a mild narcotic that is chewed throughout Yemen.

An official at a hospital run by Doctors Without Borders (MSF) said on Tuesday the facility had received the bodies of 41 people killed in the raids.

But the charity disputed the claim on Wednesday.

"MSF's hospital in the region received 44 people wounded in the incident, two of whom died," the group's Yemen project coordinator Juan Prieto said.

The rebel-run sabanews.net website said on Tuesday that the coalition carried out two raids targeting the market and a restaurant in the area and gave a toll of 65 civilians dead and 55 wounded.

The coalition launched its campaign against Iran-backed rebels in support of the Yemen's internationally recognised government on March 26 last year.

Rights groups have repeatedly urged the coalition to avoid causing civilian casualties.

A Red Cross spokeswoman told AFP there was "confusion" over Tuesday's market strike in the town of Mustabaa.

"It's difficult to obtain precise information," said Rima Kamal.

The World Health Organisation says more than 6,200 people have been killed in the conflict since March 2015 and the United Nations has warned of a "human catastrophe unfolding in Yemen".