Protesters have hung pro-Tibet slogans around the necks of China's Terracotta Warriors at a London exhibition.
The terracotta warriors are more than 2,200 years old
Placards stating "boycott the Chinese Olympics" and "stop killing Tibetans" were put on the British Museum models.
Martin Wyness, 50, and Mark Trepte, 47, hung the signs on the 2,200-year-old exhibits. Security guards stopped the pair and they were cautioned by police.
Demonstrations against Chinese rule in Tibet's capital, Lhasa, ended in violence last week.
A spokeswoman for the British Museum said a security alarm was activated as one of the protesters approached the exhibit.
None of the exhibits were damaged and the exhibition was not closed, she added.
This is the second protest Mr Wyness has launched against Chinese policies at the exhibition.
Last October he hung masks on two statues bearing the slogan "CO2 emission polluter" to highlight China's poor environmental record.
On Tuesday Mr Wyness said he wanted people in Britain to be aware of ongoing brutality in Tibet.
"I was amazed that the bulk of people clapped when I did it, showing the British public is already behind Tibetans," he said.
"I want athletes to boycott the Olympics. Human life is more important than sport."
Mr Trepte said he wanted to show solidarity towards Tibetans who are opposing China.
"It's the first time I've done anything like this," he added.
Protests began in Lhasa on 10 March - the anniversary of the 1959 Tibetan uprising against Chinese rule - and gradually escalated, culminating in a day of violence last week.
China said 13 people were killed by rioters but Tibetan exiles said 99 died in clashes with authorities.
The museum's exhibition of China's 2,200-year-old army of terracotta warriors has drawn large crowds since opening in September.
The 12 statues in the British Museum are on loan from China's collection of about 8,000 life-size warriors built to protect the First Emperor in the afterlife.