Burnum Burnum, a battler for the cause of the Aborigines, died on Sunday in his home in the Sydney suburb of Woronora. He was 61.

He died of a heart attack aggravated by a history of diabetes, his family said.

The tall, imposing Mr. Burnum Burnum brought a gift for showmanship to his fight on behalf of Australia's indigenous people. His most memorable stunt came in 1988, exactly 200 years after the first English settlers came ashore in Australia, when he laid claim to England on behalf of the Australian Aborigines.

The symbolic gesture of defiance was played against the pomp and ceremony of the bicentennial celebrations. While dignitaries in London and Canberra were making speeches extolling the great Australian nation, he climbed the cliffs of Dover and planted the red, yellow and black Australian Aboriginal flag.

Gray beard flowing, brown eyes flashing, he made a speech full of barbed allusions to the treatment of the Aborigines by the English settlers of Australia. No harm, he promised, would come to England's ''native people'' from his invasion. Nor would he poison their water, lace their flour with strychnine, or introduce them to alcohol and toxic drugs.