Skye chieftain is forced to sell off the clan's mountain range to pay for repairs to his roof

They are, arguably, the most famous and certainly the most dramatic mountains in Britain, beloved by Sir Walter Scott and owned for nearly a millennium by one of Scotland's most successful clans.

Yesterday, they were put up for sale.

John MacLeod of MacLeod, the 29th Chief of the Clan MacLeod, revealed that the Black Cuillins, said to have been named after the Celtic hero Cu Chulainn and covering 35 square miles of the Isle of Skye, are on the market. Economic realities have forced the family to give up what their island rivals, the Macdonalds, could never seize by force. Offers in excess of £10m are invited.

In a scene reminiscent of the BBC series, Monarch of the Glen, Mr MacLeod, 64, sitting beside his son and heir, Hugh, who makes corporate videos in London, said that the sale was the only way to pay for a new roof on Dunvegan Castle, the family home and a major tourist attraction.

"Of course, I am sad," the clan chief said. "As Chief Seattle said when lands were lost by the native Americans, 'These are the souls of our ancestors and the rivers are the murmurings of our fathers'.

"A lot of my closest friends did not know that I own the Cuillins. They are part of myself. You don't often talk about what is part of yourself."

Mr MacLeod clearly belongs to the family's romantic tradition. Having trained at the London Academy of Music and Dramatic Art, he plays the bagpipes and the Scottish fiddle and has produced a compact disc of his Gaelic singing, entitled MacLeod of Dunvegan. He said he anticipated around 120 additional jobs would be created as a result of the improvements to the castle funded by the sale and added: "Ultimately, I consider the protection of existing jobs, and the creation of new employment to be more important than acres."

His son, Hugh, 27, is a history graduate from the University of London and expects eventually to take over the estate, which will still retain about 25,000 acres of land after the sale.

"I feel sad, too, about selling the Cuillins," he said. "But this is hard economic reality. It would be impossible otherwise to find the £6.5m we need for the roof. At the end of the day, the castle is our core business and a lot of people depend on that."

In "The Lord of the Isles" Scott said of the Cuillins' riotous profile: "A scene so rude, so wild as this/Yet so sublime in barrenness". The mountains, which may, in fact, be named after the Norse word for "keel-shaped ridge", cover a vast area. The sale includes 14 miles of coastline - where Vikings took refuge from stormy seas - two salmon rivers, a licensed campsite, a sheep farm, farmhouse, cottages and farm buildings.

Golden eagles and the recently reintroduced white-tailed sea eagle survive in the high fastnesses, while red deer roam the hills, which include Skye's highest mountain, Sgurr Alasdair (3,257ft) and 11 "Munros" - peaks above 3,000ft that are a favourite with serious mountaineers. The range, with its awe-inspiring, jagged ridge, provides the most dramatic climbing in Britain.

The diverse landforms support many important species of plant, such as rare mosses and liverworts on the north-western slopes and uncommon Arctic and Alpine plants on the higher cliffs.

The sale is a blow to the MacLeods whose famous talisman, "the fairy flag", is said to have been given by the fairies to protect the clan in times of trouble and is kept at Dunvegan Castle, which has its own 15th-century "fairy tower".

When asked why, in a break with tradition, the fairy flag, made of finely woven silk, had not been flown to call for help, Mr MacLeod said: "Alas we couldn't. It is kept in a glass case now and is so fragile, we could not put it up a flagpole."

Keeping the roof on Dunvegan - the aim of this sale - has long been a preoccupation of the clan's chiefs. They were politically astute when they signed the Statutes of Iona in 1609, which proscribed the Gaelic language and forced chieftains to send their children to English-speaking schools. In the 18th century, MacLeod chiefs also avoided the worst reprisals after the defeat of Bonnie Prince Charlie, having refused to field their troops on his side during the Jacobite rebellion of 1745. It was a betrayal heightened by the fact that a Macdonald (Flora) had famously carried the prince "over the sea to Skye" and safety.

The 1847-51 potato famine nearly ruined the family and the clan chief was reduced to working as a clerk in London expressly to keep the roof on the house. However, the family was finally returned two generations later, in 1928, to live in the castle when Sir Reginald MacLeod struck lucky as one of the founding directors of the Shell oil company.

John MacLeod can date his ancestors back to Leod, the 13th-century son of a Norse king, whose arrival on Skye marks the mixing of the Viking and Gaelic traditions in the clans. The present chief's great grandfather was asked in 1904 whether he would consider being King of Norway, an offer he turned down.

Yesterday, Mr MacLeod said that he had consulted otherMacLeods around the worldabout the sale of the mountains. He said: "I asked the president of the clan's society in America how he thought the clan would feel if I sold the Cuillins. He said that he thought they would be fine about it. After all, the Clan MacLeod's motto is 'Hold Fast'."