Yemen's Houthi group has claimed that its forces crossed the border into neighbouring Saudi Arabia, which leads a military coalition against them, and took control of more than 20 positions.

Speaking to Yemen's SABA news agency, Houthi spokesman Yahya Sarei said on Wednesday that the military sites in the kingdom's southwestern Najran province were captured in a "surprise" offensive carried out over the past three days.

The spokesman said that more than 200 personnel affiliated with the Saudi-UAE-led military coalition battling the Houthis had been killed or wounded, while many others were captured along with large quantities of military equipment.

"We have extensive video footage of the operation which will be broadcast later," Sarei was quoted as saying.

His claims could not be independently verified. There was no immediate comment from Saudi Arabia or the military coalition.