Washington, December 27 (AFP) - The United States voiced concern Friday at the reported sentencing of an expatriate Tibetan scholar to 18 years in jail, 15 months after he was first detained while visiting his Himalayan homeland.

"The United States is of course concerned about the reported sentencing of Ngawang Choephel by the Chinese judicial authorities to 18 years in prison," State Department spokesman John Dinger said. The spokesman also rejected Chinese suggestions that Choephel was engaged in undercover activities for the United States at the time of his arrest in September 1995.

Choephel, an ethnomusicologist, appears to have been pursuing his professional interest in Tibet's traditional music and dance, the spokesman said, adding: "We have no independent information that he was in fact involved in any other activities."

"The United States has repeatedly made clear that we are concerned about the preservation of Tibet's unique cultural, linguistic, and religious heritage," he said.

"Separately, we continue to urge the Chinese authorities to release all those held for the peaceful expression of their political or religious views," Dinger said.

In a letter to a US Congressman dated October 15, a counsellor at the Chinese embassy in Washington said Chinese authorities believed Choephel was sent on a US-funded spying mission in Tibet. "We have learned that, funded by some Americans, Ngawang Choephel was sent by the Dalai Lama's 'government-in-exile' to Tibet, where he used the cover of collecting Tibetan folk songs to gather sensitive intelligence and engaged in illegal separatist activities," the letter said. Choephel, who was studying in the United States on a Fulbright scholarship, was charged with violating a broad security law against acts aimed at overthrowing the socialist system or stealing state secrets for an enemy. He was traveling in Tibet in August and September 1995 when he abruptly disappeared.

The Tibetan government-in-exile, based in the northern Indian town of Dharamsala, has also strongly denied that it had sent Choephel on a spying mission.

Chinese troops invaded Tibet in 1951 and subsequently annexed remote Himalayan territory.

The Dalai Lama, the highest-ranking leader in Tibetan Buddhism, fled to India in 1959 after a failed uprising against China. Choephel grew up in Dharamsala, India, where the Dalai Lama's government-in-exile remains.