eatery near Kathmandu's Boudhanath Stupa, one of the world's holiest Buddhist shrines, terrifying tourists who were having breakfast.
"At around 8:20 am (0235 GMT), a man in his early 20s arrived at a restaurant on the premises of the Boudhanath Stupa. He went straight to the toilet and poured petrol over his body and set himself alight," he said.
The Tibetan government in exile, based in the Indian town of Dharamshala in the foothills of the Himalayas, had previously put the number of self-immolation attempts since 2009 at 99, with 83 of them leading to the death of the protester.
The wave of gruesome protests, most cases of which occur in Tibetan-inhabited areas of China, are seen as a sign of desperation in the community over perceived religious persecution in Chinese-ruled Tibet.
Speaking to AFP ahead of the milestone of 100 cases, the prime minister of the Tibetan exile government Lobsang Sangay blamed Chinese authorities and called for the international community to take note.
"Because there is no freedom of speech or outlet for any form of protest, unfortunately Tibetans have chosen self-immolations," he said in an interview in Dharamshala.
"To the international community I say 'stand up for Tibetans'. The Chinese government has completely militarised the Tibetan area," he added.
Beijing blames the Dalai Lama, the Nobel Peace Prize winner and exiled Tibetan spiritual leader, for encouraging the immolations and points to huge investment it says has brought modernisation and a better standard of living to Tibet.
The Dalai Lama fled Tibet in 1959 after a failed uprising and has since based himself in the Indian hill town of Dharamshala.
He has appealed to Tibetans not to resort to drastic protests.
His office in New Delhi confirmed the 100th immolation attempt involved a monk, with representative Tempa Tsering calling it "very unfortunate."
Nepal, home to around 20,000 Tibetans, is under intense pressure from Beijing over the exiles, and has repeatedly said it will not tolerate what it calls "anti-China activities".
"It's a sacrifice for the Tibetan people's struggle for freedom," a Tibetan community activist in Nepal said of Wednesday's protest, asking not to be named because of fears over possible reprisals.
"People are no longer afraid to go to this extent because (oppression) has crossed the limit."
The man who set himself on fire has been sent to hospital in a critical condition, Nepal police said.
"His entire body was caught in the flames. At the hospital he tried to speak but couldn't," Adhikari told AFP.
The officer said it was not yet clear if the man had been shouting slogans protesting against China's rule in the Himalayan region of Tibet when he set himself alight.