(ANSA) - Venice, November 20 - An Italian mountaineer who conquered K2 in 1954 died on Friday, six months after the companion who stepped onto the world's second-highest peak for the first time with him.

Lino Lacedelli, who would have turned 84 on December 4, had a heart operation in the summer from which he never recovered, his family said.

His medical condition prevented him from attending the funeral of Achille Compagnoni, his fellow K2 hero, who died on May 13 aged 94.

The pair kept to their graves the secret of who actually stepped onto the top of K2 first.

"We got there together," they insisted over the years.

Lacedelli was saluted by Italian climbing legend Reinhold Messner who said: "Lino Lacedelli will go down in history not only as the conqueror of K2 with Achille Compagnoni but also as one of the greatest climbers (ever)".

"Lacedelli was one of the finest climbers of the 1950s. He achieved feats in the Dolomites which still seem incredible today," said Messner, who is often cited as the world's greatest-ever climber.

"Lacedelli contributed to the psychological reconstruction of Italians after the Second World War," said Messner, 65, the first man to make a solo ascent of Everest without supplemental oxygen and also the first to climb all 14 of the world's peaks higher than 8,000 metres.

The conquest of K2 on July 31, 1954, just over a year after Edmund Hillary and Tenzing Norgay conquered Everest, "was a real tonic for the self-esteem of an entire nation," Messner said.

Agostino Da Polenza, the head of Italy's K2 commemoration committee, recalled: "Lino Lacedelli had a bone-crushing handshake that showed just how strong he was".

"He was a very strong climber, physically imposing, able to stand up to conditions on the highest mountains".

"Compagnoni was the mind and Lacedelli the legs in the expedition".

Lacedelli, a plumber by trade, was also a mountain guide and a ski instructor in his native Cortina.

He was a pioneer of free climbing and first climbed the famous Cinque Torre at Cortina at the age of 14, after running away from his father.

Lacedelli lost a thumb to frostbite in the final attack on K2. Despite this, he continued climbing and made many other headline-grabbing ascents before retiring to open a ski shop in Cortina.

In his later years he kept active in mountain rescues.

He is credited with carrying out some 200 rescues in extremely challenging conditions. The K2 coup came a few years after British and US expeditions had been defeated by the peak, generally regarded as the world's most difficult and dangerous mountaineering challenge.

It would not be conquered again for another 23 years.

The conquest, engineered by historic mountaineer and explorer, the late 'Caesar of the Himalayas' Ardito Desio, sparked wild street celebrations in Italy.

Lacedelli was 30 when he made the final assault with Compagnoni, who was 40 at the time.

He, Montagnoni and Desio, who died in 2004 at the age of 104, received Italy's one of Italy's highest civic honours, the Gold Medal for Civic Valour, in 1954.

Lacedelli received the crowning honour, becoming a Knight of the Grand Cross, in 2005.

BONATTI CONTROVERSY.

Some observers said that Compagnoni was passed over for that because of a long-running dispute about what happened on the final ascent.

The achievement became clouded soon after the mission returned because of Compagnoni's claims that a younger climber, Walter Bonatti, then 24, bungled and prevented a planned attempt without oxygen.

Bonatti countered by claiming his companions wanted to exclude him from the last climb because he was allegedly the strongest member and the only one who might have pulled off a conquest without oxygen tanks.

In the event, oxygen tanks were used to get to the top.

Expedition leader Desio opted to keep silent on the affair and there was even talk of a cover-up - also over the plight of a local climber, Mahdi, who lost his fingers and toes bringing the tanks up to the final tent with Bonatti.

The row hit the Italian courts in the 1960s and was settled by a controversial ruling in the 1990s. The Italian Mountaineering Club accepted Bonatti's version last year after Lacedelli had broadly agreed with it in a 2004 book. K2 is only a few meters shorter than Everest and has always been regarded as posing more threats.

Its notoriously treacherous storms and unexpected avalanches have earned it the nickname 'the Savage Mountain'.

Another top Italian climber, Mario Puchoz, died on the 1954 expedition, not far from the top.

He was first reported to have succumbed to altitude sickness but it was later established that he died of a pulmonary edema - a condition unknown at the time.

photo: Lacedelli quizzed by reporters in 1954