Nepal's government has honored two climbers who were the first to scale Mount Everest without supplementary oxygen 40 years ago.

Minister for Tourism Rabindra Adhikari praised the climbers at a ceremony Thursday in the capital, Kathmandu.

Italian Reinhold Messner and Austrian Peter Habeler reached the summit without the use of supplementary oxygen, while others on their team used bottled oxygen. Until then, all climbers carried oxygen cylinders to aid them at high altitudes where oxygen levels are low.

Since Everest was first scaled in 1953, thousands of climbers have reached the summit and hundreds more make an attempt every year. This year nearly 350 foreign climbers have already been issued climbing permits. Most climbers continue to use supplementary oxygen.