BEIJING—China fined eight international shipping companies a total of 407 million yuan ($63 million) for alleged price fixing in the latest example of its increasing use of its eight-year-old antimonopoly law.

The fines focused on companies that transport cars and other vehicles to and from China, the National Development and Reform Commission said in a statement Monday. The agency, China’s top economic-planning body, said the eight companies agreed among themselves to keep freight rates at high levels.

The imposed fines are equivalent to 4% to 9% of the companies’ international shipping sales related to China, the agency said. The investigation lasted for more than a year, the NDRC said.

South Korean shipping company Eukor Car Carriers Inc. was ordered to pay 284 million yuan, the largest single fine. “We are glad to see the investigation come to an end, so we can move forward,” Craig Jasienski, chief executive and president of Eukor, said in a statement.

Wallenius Wilhelmsen Logistics, based in Oslo, was fined 45 million yuan, the second-largest amount. Japan’s Mitsui O.S.K. Lines Ltd. was ordered to pay the third-largest fine, 38 million yuan.

The agency didn’t fine Japan’s Nippon Yusen K.K., citing its cooperation.

The companies said they accepted the NDRC’s conclusions.

China in recent years has stepped up its enforcement of its antimonopoly law, gradually making it a major factor in international deals and trade. Last year, it effectively killed a three-way shipping alliance, saying the group would have too much sway over Asia-to-Europe shipping lanes. Two years ago, China approved the merger of mining companies Glencore International PLC and Xstrata PLC only after they agreed to sell a major copper project in Peru. It was sold a year later to a Chinese consortium.

The NDRC oversees the pricing part of the antimonopoly law and has also been increasingly active. In February, it fined U.S. chip maker Qualcomm Inc. $975 million and required it to change some of the way it licenses its patents for mobile phones. Last year, the agency fined Japanese auto-parts makers $200 million and Audi AG’s China joint venture about $41 million over pricing issues.

U.S. officials and foreign business groups have complained about the probes, with businesses saying enforcement has focused on foreign companies. Chinese officials dismissed the criticism, saying that domestic companies have also been targeted.

Many of the probes, such as in the case of Qualcomm, have come amid similar probes in other places, such as Europe and South Korea

via WSJ