NEW DELHI, July 28 (Reuter) - The ailing mother of a Tibetan musician sentenced by China to 18 years imprisonment for espionage appealed to the world on Monday to support her campaign for his release.

"I am getting old and my health is worsening. It seems I will not live long and I long to see my son before I die," Sonam Dekyi, 60, told a news conference.

She said her 30-year-old son, Ngawang Choephel, disappeared in August 1995, a month after he arrived in Tibet to study traditional culture and music. In December 1996, China said he had been detained on charges of spying.

Crying during most of her statement, Dekyi, a tuberculosis patient, begged for her son's immediate release and insisted he had nothing to do with politics.

"The international community knows my son went to Tibet to conduct in-depth research on ancient Tibetan culture and music," Dekyi said.

"It seems my son was made to confess to being a spy for the Tibetan government-in-exile by the Chinese authorities after he was subjected to severe torture and inhuman prison conditions," she added.

She said she had applied several times to the Chinese embassy in New Delhi for a visa to visit Tibet, and was told it would take up to four months for her application to be processed.

"I cannot wait that long," Dekyi said. "I am ailing from tuberculosis and the pain of my son's imprisonment is enormous."

A music teacher in India and a Fulbright scholar of ethnomusicology from the United States, Choephel was a student of Tibetan music and culture at the Tibetan Institute of Performing Art in the Himalayan Indian town of Dharamsala.

Thousands of Tibetans fled their homeland in 1959 with their spiritual leader, the Dalai Lama, after an abortive uprising against China's annexation of Tibet.

Some 130,000 Tibetan refugees are now settled in different parts of India.

The Dalai Lama's headquarters are in Dharamsala.

The Dharamsala-based Tibetan Centre for Human Rights says China arrested at least 445 Tibetans in 1995, and 12 cases of death due to torture were recorded.

It says that in December 1996, more than 1,000 political prisoners were known to be in detention in Chinese prisons in Tibet.