Dalai Lama has been trying to reach a compromise with the Chinese government over the fate of his people.

The US ambassador to China has called on Beijing to open a "substantive dialogue" with the Dalai Lama in remarks made this week during a rare visit to Tibet, his embassy said Saturday.

Terry Branstad visited northwest China's Qinghai province -- home to many Tibetans -- as well as the Tibet Autonomous Region, where access is restricted for diplomats and journalists.

"He encouraged the Chinese government to engage in substantive dialogue with the Dalai Lama or his representatives, without preconditions, to seek a settlement that resolves differences," an embassy spokesman told AFP via email.

China is accused by human rights groups of repressing Tibet's religion and culture, and cracking down on separatism.

Beijing says it protects religious freedom and has invested heavily to modernise the region and raise living standards.

Since fleeing to India in 1959 following a failed uprising in the Tibetan capital Lhasa, the Dalai Lama has been trying to reach a compromise with the Chinese government over the fate of his people.

Having initially called for Tibet's independence, the Buddhist leader is now campaigning for greater autonomy. But negotiations with Beijing have stalled since 2010.

Observers accuse China of running down the clock until the death of the 83-year-old religious leader.

During his visit to Lhasa, Branstad visited the Potala Palace -- the former residence of the Dalai Lama -- as well as Tibetan Buddhism's holiest temple, the more than 1,300-year-old Jokhang.

He met with senior Tibetan religious and cultural leaders.

"He also expressed concerns regarding the Chinese government's interference in Tibetan Buddhists' freedom to organise and practice their religion," the embassy spokeswoman said.

"The Ambassador raised our long-standing concerns about lack of consistent access to the Tibetan Autonomous Region," she added.

In order to visit Tibet, foreigners require a special permit. For tourists it is usually relative easy to obtain, but for diplomats and in particular journalists it is more difficult.