THE late Duke of Atholl lost a six-figure sum in a #50m fraud involving an American investment firm, it has been claimed in a US court action.

The tenth Duke of Atholl was questioned by American investigators shortly before he died last year. The US legal team were investigating an alleged stock market sting which left thousands of people, including at least eight Britons, out of pocket.

The investigation centres on US firm AR Baron. It has been alleged in the Manhattan State Supreme Court that the stock exchange company was set up with the sole intention of defrauding clients.

The Duke of Atholl and Pilkington Glass chairman Sir Antony Pilkington are both named as significant investors in the court papers. They are among 8000 investors who are said to have lost ''small fortunes'' through the company.

Mrs Rosemary Walker, spokeswoman for Atholl Estates, confirmed that the former Westminster Press chairman had lost thousands between 1994 and 1996.

''I know it is true,'' she said ''because the Duke discussed it with his estate manager. We are not sure exactly how much money is involved because it was a personal thing and we obviously cannot now ask the Duke.

''Nobody at the Blair Atholl estate knows very much about it and the whole matter has been put in the hands of his American lawyers.''

She said the death of the tenth Duke, Iain Murray, had left matters of inheritance confused as the money invested in New York was from the former National Trust for Scotland president's personal wealth.

''I really do not know who would stand to benefit from it if they managed to get any of the money back,'' Mrs Walker said.

The famous thirteenth century family seat in Perthshire, with the 120-bedroom Blair Castle and 70,000 acres of prime farmland, was put into a charitable trust when the 64-year-old bachelor died.

His closest living heir was established to be South African-based third cousin Mr John Murray, who became the eleventh Duke of Atholl and consequently head of Europe's last private army.

He will visit Scotland this weekend to take the salute at the Atholl Highlanders Parade for the first time since taking over the 100-strong army created by Queen

Victoria.

Part of the ceremonial force will then travel back to South Africa at the invitation of the Transvaal Scottish regiment and attend functions including a Highland gathering and a regimental ball.

The eleventh Duke was not available for comment on the court action at his Johannesburg home yesterday.

A spokesman for Sir Antony Pilkington, who gave pre-trial testimony to a Grand Jury, confirmed he had lost #300,000.

AR Baron was set up by 13 young stockbrokers, who now face up to 25 years in prison if found guilty on a charge of operating a criminal enterprise. They are facing a 174-count indictment after a lengthy international investigation.

The investment company, which played the money markets on Wall Street, attracted clients with an image as an aggressive go-getting young business.

But now it has been accused of stealing clients' money, misleading investors about the value of securities, and manipulating company stocks. The court action also claims it made unauthorised use of company accounts and then lied to industry regulators about its financial

status.

All 13 defendants have denied the charges. The case is likely to run for several months.