BEIJING - China's quality regulator said Wednesday that it had put 137 food companies on a warning list as they had bad records in recent inspections.

Supervision will be stepped up on those companies -- 48 food importers, 47 overseas food makers and 42 overseas exporters, according to the General Administration of Quality Supervision, Inspection and Quarantine.

Extra quality documents will be required when their products cross the border.

The companies should rectify their problems to improve food quality, and can be moved off the list when they meet the administration's requirements.

As the authority improved the supervision network for imported food and toughened inspection and quarantine, 35,000 tons of imported food products failed to pass quality inspections in 2016, up 325.2 percent year-on-year.

With the improvement of Chinese people's lives, demand for imported food products has been on the rise. In the past five years, the value of food imports rose by an annualized rate of 2.6 percent.