A search operation was under way after an avalanche struck Pakistan's Broad Peak, leaving a 10-member international climbing team led by renowned mountaineer Nirmal Purja, better known as Nimsdai, missing, Pakistani mountaineering officials said.

The avalanche hit around midday on Thursday on the 8,047-metre peak in the Karakoram range, according to the Alpine Club of Pakistan, severing contact with the expedition.

"The entire team has reportedly been out of communication since the avalanche," Karrar Haidri, senior vice-president of the Alpine Club of Pakistan, told Everest Chronicle.

Tracking data accessed by Everest Chronicle shows that Nimsdai had reached an altitude of 6,659 metres, above Camp II on Broad Peak, at 9:38 a.m. local time on Thursday. The tracker then recorded a rapid descent of about 800 metres to 5,891 metres at 10:18 a.m., consistent with the reported avalanche. No further location data has been transmitted from Purja's tracker since then.

The missing team includes five Nepali climbers led by Nimsdai, the Nepal-born former British special forces soldier who won global acclaim after climbing all 14 of the world's mountains above 8,000 metres in just over six months in 2019.

Also on the expedition are Pakistani climber Sohail Sakhi from Hunza, Omani mountaineer Nathira, American climber Mallory Geis, a Chinese climber identified as Wang, and another foreign climber, officials said.

Major General Irfan Arshad, president of the Alpine Club of Pakistan, said the organisation was coordinating with government authorities and rescue agencies to launch an emergency response.

"Every possible effort is being made to ensure that helicopter support and all available rescue resources are mobilized at the earliest opportunity, subject to weather and operational conditions," the club said in a statement.

"The Alpine Club of Pakistan is closely monitoring the situation and coordinating with all concerned stakeholders," it added, saying it stood with the climbers' families and the international mountaineering community.

There was no immediate confirmation of casualties or survivors.

Mingma David Sherpa, co-founder of Elite Exped, confirmed the incident and said a search helicopter was expected to reach the area early Friday, weather permitting.

Broad Peak, the world's 12th-highest mountain, lies on the Pakistan-China border near K2. Avalanches remain one of the principal hazards.

The incident comes just nine days after Nimsdai climbed Pakistan's Gasherbrum II without supplemental oxygen, completing the 57th successful ascent of an 8,000-metre peak in his career.

The ascent left him with only Cho Oyu remaining to complete his self-declared "Hat-Trick Project" — climbing all 14 of the world's 8,000-metre peaks three times while also completing the Seven Summits three times.

Purja, who was born in Nepal and later became a British citizen after serving in the British Army's Special Boat Service, has said the project aims to raise more than £1 million for the Nimsdai Foundation, which supports humanitarian and education initiatives in Nepal.

One of the foundation's flagship projects, the Lobuche Porter House, opened in the Everest region in May, providing accommodation for porters working on trekking and climbing expeditions.

The Karakoram climbing season is currently at its peak, with expeditions also attempting K2, Gasherbrum I and Broad Peak. Nepali rope-fixing teams are positioned at Camp II on several peaks, while two Nepali-led teams reached the summit of Gasherbrum II on Thursday.