He said the information came from a 'person of trust' who had telephone contact with the region. He had been told food and water was not being allowed to be transported into the three main central Tibetan monasteries, Drepung, Ganden and Sera.
Grader added that Tibetans injured in the unrest were being denied medical treatment, saying the Indian-based 'government in exile' had been told that hospitals and doctors were forbidden to treat Tibetans.
He said the demonstrations had been continuing mainly in eastern Tibet, whereas in the capital Lhasa there had been large-scale searches of homes and mass arrests. Thousands of Tibetans had been taken to Chinese prisons outside Tibet.
His claims could not be checked, as Western journalists have been excluded from Tibet.
A German newspaper, Bild am Sonntag, reported earlier that Tibetans living in Germany complained they were under surveillance by Chinese authorities.
'Chinese spies from the embassy and consulates intermingle with our demonstrators. They try to spy on us or break up our meetings,' it quoted Tsewang Norbu of the Association of Tibetans in Germany as saying.
He asserted that telephone conversations between Tibet and Germany were being tapped by the Chinese security services.