VANCOUVER -- Sixteen temporary employees at a controversial coal mine in northern B.C. are returning to China because of the company's concerns about ongoing litigation and its associated costs and disruptions.

HD Mining announced on Monday evening that it has also decided not to bring any more workers to the proposed Murray River coal project near Tumbler Ridge, B.C., until it has "reliable certainty" on the project.

Two unions have been challenging in court the federal government's decision to allow the company to bring 201 Chinese miners to the community instead of hiring Canadian workers.

"This was a difficult decision for us, but we are very concerned about the cost and disruption this litigation brought by the unions has caused to the planning of the project," said Jody Shimkus, vice-president of environmental and regulatory affairs for the company, in the media release.

According to the company, the 16 workers participated in underground preparation work on a bulk 100,000-tonne coal sample.

The company did not indicate how much the litigation has cost, nor how the litigation has delayed preparatory work but said it remains committed to the project, noting it will continue work on its housing development and the environmental assessment process.

"But we need to be able to rely on the Canadian legal system -- and receive fair treatment from governments -- when planning and developing projects," said Penggui Yan, chairman of HD Mining, in a statement.

"In the absence of being able to find Canadians qualified and interested to do this work, we need to know we can rely on the two-year temporary foreign worker authorizations we received."

The International Union of Operating Engineers and the Construction and Specialized Workers Union have been challenging a decision by the federal government to issue permits to 201 temporary foreign workers.

That judicial review is slated to take place in April.

The company has argued it made significant efforts to recruit qualified Canadian workers and met or exceeded all the requirements of Human Resources and Skills Development Canada in obtaining temporary foreign worker permits.

But earlier this month, the company reluctantly agreed to turn over to the unions the resumes of hundreds of job applicants who were turned down.

The Canadian Human Rights Commission also rejected a complaint filed by a Chinese miner against the United Steelworkers, over the union's vocal campaign against the workers.

The worker argued that the union allegations were "likely to create contempt for Chinese persons and in particular Chinese mining workers."

HD Mining said it will continue to "vigorously contest" the unions in court.