"This is not an open place. You can't be here," a police officer told three AFP journalists shortly before ordering them out of the town of Lajia, a Tibetan-populated area of mountainous Qinghai province, which borders Tibet.
Foreign reporters are not allowed to travel into Tibet independently, but are allowed to visit neighbouring areas.
Monks at the Lajia Tibetan Buddhist monastery had declined to talk to AFP, apparently out of fear of police reprisals.
The AFP team saw checkpoints on roads coursing through the rugged, mountainous area, with more than 20 police in full riot gear patrolling the nearby town of Guomaying.
Other foreign journalists have reported troops being deployed across the Tibetan plateau to stop any protests for the highly sensitive 50th anniversary of a failed uprising in 1959.
About six million Tibetans live in Tibet and the neighbouring provinces of western China such as Qinghai.
In Tibet's capital Lhasa, residents said armed police were on patrol, including near the Jokhang temple, Tibet's holiest site that was a focal point for protests 12 months ago against Chinese rule.
"Our hotel is near the Jokhang temple and there are armed police around it. You need to keep your identification with you because the police are checking," said a female receptionist at a Lhasa hotel.
The 1959 uprising led to the Dalai Lama fleeing his homeland and the Tibetan spiritual leader decried on Tuesday the fate of his people in the ensuing 50 years.
The 73-year-old said from his exiled base in India that China had brought "untold suffering and destruction" to Tibetans in waves of repressive campaigns.
"These thrust Tibetans into such depths of suffering and hardship that they literally experienced hell on earth," he said.
One Tibetan man in Qinghai's capital, Xining, gave a first-hand account of the fear for many in the current climate, amid reports that hundreds of people have gone missing in a security sweep since last year's unrest.
"I'm really scared because, even though I do the right things, I'm just the wrong person for this government," said the man, who AFP did not name to prevent any potential police reprisals against him.
In Lhasa and towns across the Tibetan plateau, residents reported intense patrols by armed security forces that appeared to have warded off any immediate protests to mark the anniversary.
"Armed police are patrolling the streets 24 hours a day. The number of police has increased in the last 10 days," a male resident of Guide, a Tibetan county in Qinghai, told AFP by phone.
"We are not allowed to hold any (public) activities here, all such activities have been forbidden," said the man.
He said authorities cancelled plans to mark International Women's Day last weekend.
In Xiahe county, Gansu province, where local monks protested during last year's unrest, an employee told AFP his hotel was booked out by officials from the local "stability protection office".
"There are no rooms available for tourists. We got a notice from the provincial government saying tourists are forbidden from entering the area until mid-April," said the man, who added riot police were patrolling streets.