A Chinese foreign ministry spokesman, Liu Jianchao, Tuesday called the Spanish court's decision to hear the charges interference in China's internal affairs.
"The so-called genocide in Tibet is complete and sheer libel and fabrication against China," he said. "The Tibet issue is purely a question of China's internal affairs. We are opposed to the attempt of any country to interfere in our internal affairs under the pretext of the Tibet question."
The Madrid-based Committee to Support Tibet filed a suit with a Spanish court last June, under a law that allows prosecution of human rights crimes committed in other countries.
The human rights organization accuses former Chinese President Jiang Zemin and six other top officials of ordering massacres and torture in Tibet.
The lawsuit claims over one million Tibetans have been killed or have disappeared since China occupied Tibet in 1950.
Tibet's Buddhist spiritual leader, the Dalai Lama, fled into exile in India in 1959 after a failed uprising against communist rule.
The Spanish court will hear witnesses before deciding whether to file charges against those accused in the lawsuit. Proceedings began Monday with testimony from an exiled Tibetan now living in Spain.