The two envoys who represented the Dalai Lama in failed talks with China on Tibet over the past decade have resigned to express their frustration over Beijing's unwillingness to consider any autonomy for the Himalayan region.

Officials announced the resignations of Lodi G. Gyari and Kelsang Gyaltsen in a statement Monday from the Tibetan government-in-exile based in the northern Indian town of Dharmsala. The two men had held nine rounds of talks with Chinese officials from 2002 to 2010.

Gyari and Gyaltsen said in a resignation letter that the situation in Tibet has worsened since large-scale public protests there in 2008, and that recent self-immolation protests in the region have added to their frustration with China's handling of the region.

"At this particular time, it is difficult to have substantive dialogue," the letter said.

In 2008, the envoys presented a proposal to grant Tibet greater autonomy within China, but Beijing rejected the plan. Chinese officials have repeatedly refused to discuss the status of Chinese-ruled Tibet, saying they would only address the return of the Dalai Lama, the spiritual head of Tibetan Buddhists who fled to exile in India in 1959. Beijing has accused him of trying to split the country, a charge he denies.

China says Tibet has always been part of its territory and has sought to win over its population by boosting economic growth. But many Tibetans say their region was virtually independent for centuries until Chinese troops invaded in the 1950s, and say their language and culture are now being suppressed.

The Dalai Lama stepped down as the political leader of the Tibetan people in 2011, the same year that Harvard legal scholar Lobsang Sangay was elected prime minister of the exile parliament.

Gyari and Gyaltsen continued to be described as envoys of the Dalai Lama, but have also reported to Lobsang Sangay since he took office.

Tibetan government-in-exile official Thupten Samphel said there was no urgency to name new envoys because Beijing is showing "no willingness" for dialogue. New envoys would be named once Chinese officials send "a positive signal," he said.