JAMMU, India, June 9— Dhirendra Brahmachari, a spiritual leader and yoga instructor who became a confidant of Prime Minister Indira Gandhi, died today in a plane crash. He was 70.

A private plane carrying Mr. Brahmachari and his pilot hit a pine tree and burst into flames while landing at his Hindu religious retreat and yoga school in Mantalai, the police said. The pilot was also killed.

Mr. Brahmachari taught yoga to India's first Prime Minister, Jawaharlal Nehru, and his daughter, Indira Gandhi, who became Prime Minister in 1966. He became politically powerful in 1975-77, when Mrs. Gandhi dissolved Parliament, declared a state of emergency and suspended civil liberties.

Known throughout India as "the Flying Swami," he not only helped Mrs. Gandhi reach decisions and make appointments, but carried out some of her orders. He also operated popular yoga institutes in New Delhi, Mantalai and other towns in northern India, where he was reported to have received plots of land through his connections with Mrs. Gandhi. She was assassinated in 1984.

Mr. Brahmachari was charged with buying an aircraft in the United States during the state of emergency and smuggling it into India without paying customs duties, but he was never tried. Dozens of other criminal cases were filed against him and many are still dragging on in the courts. In one instance, he was accused of illegally importing gun parts from Spain for his factory, which had a license to make guns only with local materiel.