Police in Myanmar used water cannon and tear gas on Thursday to break up a protest against expansion at a copper mine in the north-west of the country.
Protesters said dozens were injured and their camps set alight in the town of Monywa.
Farmers, monks and activists have been protesting since June against forced evictions to enable expansion of the mine.
Laws on public protests in Myanmar (formerly known as Burma) have been relaxed amid a series of democratic reforms. But this week the government gave the protesters an ultimatum to leave the site.
A BBC correspondent says the protest is seen as a test case for how new government will handle growing protests around the country over land grabs that took place under military rule.
The farmers started protesting in June, saying they were forced to accept a deal two years ago under which they gave up their land in return for new housing and financial compensation.
The mine is owned by the military and Norinco, a Chinese arms manufacturer. The expansion project covers several thousand hectares of land in the Sagaing region.
President Thein Sein's office said in a statement that police used water cannon, tear gas and smoke bombs to disperse the crowds. A spokesman denied that chemical weapons were used.
Opposition leader Aung San Suu Kyi is in the area and says she wants to mediate a settlement.