The Dalai Lama will undergo further medical tests in Mumbai, India. The Dalai Lama will undergo further medical tests in Mumbai, India. (Ted S. Warren/Associated Press)

The Dalai Lama has cancelled trips to Mexico and the Dominican Republic after doctors diagnosed him with exhaustion, his spokesman said Wednesday.

Thupten Samphel said the Dalai Lama has been experiencing some discomfort, and needs to rest and undergo medical testing. The Tibetan spiritual leader will be out of the public eye for at least three weeks, according to his website.

The tests will be done in the Indian city of Mumbai, and then the Dalai Lama will recuperate in the northern Indian town of Dharamsala, where he has lived in exile since 1959.

The Dalai Lama has been undergoing tests in Mumbai since early August, so the latest round will complete the work that was already started, according to the Dalai Lama's website.

"He has been going to Mumbai for regular health checkups on advice from his doctors for quite a long time," said Samphel, who would not provide further details on the spiritual leader's condition.

While the Dalai Lama, 73, is generally thought to be in good health, this is not the first time exhaustion has laid him low. In 2006, he cancelled his appointments for a month on the advice of doctors.

The Dalai Lama usually spends several months a year travelling the world to teach Buddhism and raise awareness to the struggle Tibetans face as they lobby for greater freedom from China.

Tibetan Buddhists say the spiritual leader is the 14th reincarnation of the Dalai Lama. According to centuries-old tradition, monks search for the reincarnation of the lama after a spiritual leader's death.

The Dalai Lama last year floated the idea of breaking tradition and naming his own successor while still alive, or letting monks elect the next spiritual leader.

He suggested the change after China issued an order saying it must approve Tibet's future spiritual leaders, fuelling concern that China may forcibly choose a pro-Beijing leader once the current Dalai Lama is dead.

With files from the Associated Press