Kathmandu, April 29 - Top Italian mountaineer was among three European climbers attacked by some 100 sherpas for allegedly meddling with their work, The Himalayan Times said Monday. Moro, Swiss Ueli Steck and Briton Jonathan Griffith were reportedly set upon at a base camp on Mt Everest. Moro was slightly injured while Steck had to be taken to hospital in Kathmandu. The Times said the incident "could have been much more serious if other foreign climbers had not intervened" to try to protect the three. The Nepalese police have opened a probe into the attack while Nimanuru Sherpa, head of the Cho-Oyu Treks agency which helped set up the expedition, said he was "upset". "This episode risks tarnishing Nepal's image around the world," he said. Moro has gained fame for climbing some of the world' highest peaks without oxygen. Three years ago Moro and Kazakh colleague Denis Urubko made the first-ever out-of-season ascent of Makalu, the world's fifth-highest peak, battling gale-force winds. Mountaineers had been trying to make a winter ascent of the 8,462-metre Makalu for 30 years, but the peak known as The Big Black had foiled some of the world's best climbers. Among those who it defeated were Italian great Reinhold Messner, who tried the climb twice, and French mountaineer Jean-Christophe Lafaille, who disappeared during a solo attempt in 2006. Bergamo-born Moro, 45, was the first man in the world to climb another 8,000-metre Himalayan peak, Shisha Pangma, during winter. Moro says he is determined to carry out winter ascents of the peaks on the Pakistani side of the Himalayas like Nanga Parbat. He and Urubku were forced to call off an attempt on it because of bad weather last year. Another Pakistani giant, the world's second-highest mountain K2, has never been climbed out of season.