A Nepali mountaineer on Tuesday smashed the speed record for summiting the world's 14 highest peaks, racing up all "8000ers" in just six months and six days, organisers said.

The previous record for the 14 mountains above 8,000 metres (around 26,250 feet) - completed by Nirmal Purja at 8.59 am (1259 GMT) on Tuesday - was almost eight years.

"MISSION ACHIEVED! says @nimsdai from the summit of Shishapangma," read a post on Purja's Facebook page, while a statement quoted the former British elite soldier as being "overwhelmed and incredibly proud" after his 189-day feat.

"It has been a gruelling but humbling six months, and I hope to have proven that anything is possible with some determination, self-belief and positivity," the 36-year-old said.

"We started with nothing, but look how far we've come."

Starting with Italy's legendary Reinhold Messner in 1986 - who on Tuesday praised Purja's "unique mountaineering accomplishment" - around 40 climbers have climbed the Earth's 14 highest mountains, but none have come close to Purja's speed.

The late Polish climber Jerzy Kukuczka took seven years, 11 months and 14 days in 1987. South Korean Kim Chang-ho completed the challenge one month faster - although unlike Kukuczka and also Purja, he never used supplementary oxygen.

Copyright Agence France-Presse, 2019