A Chinese manager at a copper smelter in northern Zambia has been admitted to hospital after being assaulted by workers demanding better conditions.
Some Chinese mines in Zambia have poor safety records
An estimated 500 workers at the Chinese-owned Chambishi mine site started throwing stones at the managers as they attempted to hold talks.
Police came in to restore order and rescue the Chinese who had taken refuge by locking themselves in their offices.
Several buildings were burned in the violence and a protester was injured.
Last year, China's president cancelled a visit to Chambishi fearing protests.
A blast at the copper mine killed 50 people in 2005.
Chambishi Smelter, which is under construction, is part of a huge multi-million dollar Chinese investment in the area.
The BBC's Boyd Chibale in Kitwe says a kitchen for Chinese workers and a guard's house were set alight and hostel windows smashed in the violence.
Our correspondent says the workers have now gone home, and the Chinese management are in talks with the unions.
The protest was sparked by rumours that members of the Chinese management team were about to go on holiday, which workers feared would delay negotiations to improve their conditions of service.
"The Chinese are not respecting Zambian labour laws," workers' representative Teddy Chisala told the AFP news agency.
In recent years, China has emerged as one of the biggest buyers of Zambian copper.
But correspondents say Chinese investment in mining and manufacturing has not been without controversy - with constant industrial disputes amidst allegations of poor working conditions.
In elections in 2006, opposition candidate Michael Sata ran on an anti-China ticket, calling for "Zambia for Zambians".