To the Editor:

Your news item on the unveiling of Mohandas K. Gandhi's statue in New York City's Union Square (Oct. 3) referred to the dhoti the Indian leader is shown wearing as a symbol of ''Hindu asceticism.'' This is not correct.

On his return to India from South Africa in the early part of this century, Gandhi changed his mode of dress from impeccable Western to an outfit worn by men in his native state of Gujarat, which included a turban and, later, the now famous ''Gandhi cap.'' He did this effectively to identify with the Indian people, whom he was later to lead to independence.

Soon afterward, he discarded even this style in favor of a simple hand-spun dhoti, which he normally wore with nothing else above the waist. He once said he had no right to wear anything more than the barest minimum when millions of his countrymen were deprived by their British rulers of the ability to buy enough clothing ''even to hide their shame.'' It was this mode of dress that prompted Winston Churchill to call Gandhi a ''half-naked fakir.''

On Gandhi's return from a visit with the King of England at Buckingham Palace, a correspondent asked how he felt so scantily dressed in the presence of the monarch (during his stay in England, Gandhi added only a shawl to protect himself from the cold). ''There was no problem,'' the Mahatma replied with a mischievous smile. ''His Majesty more than made up for both of us.'' VASANT NEVREKAR New York, Oct. 6, 1986