Police with riot gear were deployed to move about 3,000 mostly female workers who had blocked a road outside their factory owned by Sabrina (Cambodia) Garment Manufacturing in Kampong Speu province, west of the capital, Phnom Penh.
A Nike spokeswoman in the United States told Reuters by e-mail that the company was "concerned" about the allegations and was investigating. Nike requires contract manufacturers to respect employees' rights to freedom of association, the spokeswoman added.
Sun Vanny, president of the Free Trade Union (FTU) at Sabrina, told Reuters the injured included a woman who was two months pregnant and who had lost her child after military police pushed her to the ground.
"There was a pregnant woman among them. She lost blood and then she lost the baby," he said.
According to the International Monetary Fund, garments accounted for 75 pct of Cambodia's total exports of $5.22 billion in 2011.
Low-cost labour has attracted manufacturers making clothes and shoes for Western brands but strikes over pay and working conditions have become common.
This month, two workers were killed at a factory making running shoes for Asics when part of a warehouse fell in on them. Police revised down the original death toll of three given by a minister.
A series of deadly incidents at factories in Bangladesh, including the collapse of a building last month that killed more than 1,000 people, has focused global attention on safety in factories in Asia makes goods for Western companies.
Sun Vanny said the workers making the Nike clothing had been staging strikes and protests since May 21. They want the company, which employs more than 5,000 people at the plant, to give them $14 a month to help pay for transport, rent and healthcare costs on top of their $74 minimum wage.
"Police used an electric baton to hit me on the head and if other workers hadn't pulled me away, I would be dead," Leng Pros, a 28-year-old male worker, told Reuters from his hospital bed. "I didn't know what happened next, I fell to the ground."
Police and military police officials declined to comment on the clash, saying they were still collecting reports.
