WASHINGTON — A coalition of labor rights groups stepped up pressure on retailers and apparel brands sourcing in Cambodia on Thursday, imploring them to help urge an end to the violence that has taken the lives of at least four garment workers in the past week and to change their purchasing practices to support lifting the minimum wage in that country.

The statement by the labor rights groups comes in the wake of the Cambodian government’s use of deadly force on Jan. 3 against thousands of garment workers protesting for a higher wage rate that left at least four dead and more than 30 people injured. The Cambodian government initially offered to increase the minimum wage rate to $95 a month from $80 a month, but after more protests, the government  increased the rate to $100 a month, which workers have said is still not enough. Workers are demanding an increase to $160 a month.

The labor rights coalition is now calling on global apparel brands to take immediate action and contact the Cambodia government with a list of demands, including immediately ending violence and intimidation against workers and their union representatives; releasing individuals who have been detained for participating in protests and strikes; refraining from bringing charges against trade union leaders and workers who have participated in the strikes; resuming good faith minimum wage negotiations, and holding anyone responsible for the violence accountable.

“Whilst our primary concern is the safety and well-being of those workers who have been detained, we are also calling on brands to look at the long-term implications of their purchasing practices,” said Jeroen Merk, an official at the Clean Clothes Campaign. “Until brands recognize that these practices contribute to the poverty wages received by workers in Cambodia and in turn the demonstrations we are witnessing, then no brand sourcing from Cambodia can claim to be acting fairly or decently.”

On Tuesday, seven global apparel brands, including H&M, Gap Inc. and Levi Strauss & Co., wrote an open letter to Cambodia’s Prime Minister Hun Sen, the Garment Manufacturers Association in Cambodia and six major trade unions condemning the government’s use of lethal force and urging all sides to continue negotiating a minimum wage increase.

While commending the companies for writing the letter, the labor coalition said it did not go far enough in “denouncing the reprehensible conduct” of the Garment Manufacturers Association in Cambodia, which the groups charge has condoned the government’s use of deadly force.

To that end, the coalition also sent a joint letter to several U.S. and European apparel brands and retailers, including Gap, Levi Strauss, Wal-Mart Stores Inc. and H&M over the weekend and is seeking a response to the letter by Friday, according to Liana Foxvog, director of organizing at the International Labor Rights Forum.