UN envoy Hans Grundberg held rare direct talks with Houthi chief negotiator Mohammed Abdul-Salam in Muscat over the weekend, as Yemen's war escalates at its fastest pace in years.

Grundberg disclosed the meeting in an interview with The Associated Press in Cairo on September 29. He said he also held talks in Riyadh with Yemen's internationally recognised government and Saudi Arabia. He described the recent escalation as "unprecedented" and "dramatic."

The Houthis stormed the Red Sea coast early in September, capturing Mokha and nearby islands in their biggest land grab in years. The offensive ended the 2022 ceasefire that had largely held.

Fighting is now close to Bab el-Mandeb, the strait through which about 12% of global trade passes. Attacks in the area have repeatedly disrupted commercial shipping.

United Nations figures cited by the AP put the human cost at 838 people killed, more than 3,640 injured, 145,000 displaced, and over 3,000 who fled across the sea to Djibouti.

Diplomats say the Muscat talks aim to pull the warring sides back from a wider conflict that could redraw front lines across Yemen.