Scotland's historic island of Iona, cradle of Scottish Christianity and burial place of St. Columba and 60 ancient kings, was brought today by Sir Hugh Fraser, the Scottish millionaire who owns London's famous Harrods department store.

Fraser's family foundation agreed to pay just over $3 million for the 1,900-acre island off the western coast of Scotland and then give it to the government to preserve "for the nation" its hallowed abbey church, ancient cemetery and tiny village of 80 fishermen and sheep-raising crofters.

The wind-swept island, which was owned by the Scottish dukes of Argyll for nearly 300 years, is being sold by trustees for the 10th Duke of Argyll, who died in 1973, to pay a million dollars in death taxes owed on his estate and a $2 million dollars repair bill left by a fire at the Argyll family's Inverary Castle.

Britain had been beset by rumors for months that the island might be bought by Americans for Arabs who would try to develop it as a tourist resort with hotels on its sandy beach and a golf course or two where sheep now graze on greenwards divided by rock fences. Only the abbey and graveyard were believed certain to be safe since the eighth Duke of Argyll gave them to the Church of Scotland in 1899.

But the 12th Duke of Argyll, 41-year-old Ian Campbell, who is also chief of Scotland's Campbell clan-being directly descended from Sir Colin Campbell, who was knighted in 1280, and Baron Campbell, who became the first Earl of Argyll in 1457 - insisted that he and other trustees of his grandfather's estate would sell only to someone who could afford to preserve Iona's heritage.

St. Columba, who was born in Ireland in 521, landed on Iona in 563 and made it his base for brave, wide-ranging journeys to spread Christianity throughout Scotland, Ireland and northern England. When he died in 597, he was buried outside his abbey on Iona, but his remains were stolen by Norse raiders 200 years later. There is still dispute over whether they were every returned.

For the next 500 years, Iona became the burial place of 48 Scottish, eight Norwegian, four Irish and two French kings - among them the Scottish King Duncan, buried there in 1040 after murder by macbeth. Throughout the Middle Ages, Iona was also the final resting place for fierce West Highland chieftains.

Although raiding Vikings destroyed the original abbey and the markers of most of the royal graves, the abbey built by Beneictine monks in the 13th century and the remains of the ancient cemetery have been visited by a steady stream of pilgrims and luminaries through the centuries.

Keats and Wordsworthe wrote poetry there, Sir Walter Scott found it "desolate and miserable," but Dr. Samuel Johnson visited Iona and then wrote "that man is little to be envied whose patriotism would not gain force upon the plain of Marathon, or whose piety would not grow warmer among the ruins of Iona."

Iona's historical relics and timeless way of life were never really in danger, according to Ronald Ireland of the Smith's Gore real estate firm in Edinburgh, which completed the sale to Sir Hugh Fraser "in principle" today.

On the Argyll trustees' instructions, he said, all prospective buyers would have had to present assurance that the island would somehow be preserved. The local Scottish planning mercial development of Iona. Furthermore, the Church of Scotland would be watching over the shoulder of any new owner of the three-by-one mile island, which has just a single, narrow street and no cars.

So why, Ireland was asked, did he received three firm offers of between $1 million and $2 million and many other serious inquiries from around the world even before bids could be formally considered this week?

Most of the prospective buyers, whom he would not identify, wanted to buy Iona, Ireland said, "because they felt it was important to preserve its heritage. It's like a famous painting by an old master that sells for a million pounds [$2 million]. It is that valuable because it is beautiful, because it is historic and because it is unique."

To aviod tax problems like those besetting the estate of the 10th Duke of Argyll, Ireland explained, Iona probably would have to be bought by somebody who was wealthy and had a family or charitable foundation or trust.

Sir Hugh Fraser, 42, qualified on both grounds. He inherited from his father a retailing empire topped by Harrods, the sprawling Victorian department store in the wealthy Knightsbridge area of London that prides itself on being able to sell a customer anything - from high fashions and precious art and furniture to gourment food, from live pegdiree animals to real estate. The House of Fraser firm also owns a number of prestigious specialty store in London and store chains throughout Britain and abroad.

Fraser himself, however, has not had a happy life under the pressure of continuing his father's success. He has suffered failed marriages and tragic love affairs and has been admitted compulsive gambler who once lost $500,000 in a single night in a London casino and had to sell $3 million worth of shares in an investment firm of his to pay off other gambling debts.

Last year, Fraser was found guilty with two other men of violating Britain's Companies Act for failing to give an accurate financial picture of that same investment firm when they obtained a $8.5 million loan.

Fraser said through a spokeman tonight that he was buying Iona in memory of his father, who had built the House of Fraser from a family drapery firm, acquiring Harrods, the crown jewel, in 1959.

His spokeman said Fraser would offer Iona to the British goverment's Scottish secretary, George Younger, to decide which national body should adminster it. The National Trust for Scotland had unsuccessfully offered $1.2 million for Iona and promised to raise funds to adminster it in its present state.

The island was appraised for estate purpose on the death of the 10th Duke of Argyll in 1973 at only $50,000.