FILE PHOTO - Steel rods are piled up at a scrap metal recycling yard at the edge of Beijing, China, September 21, 2016. REUTERS/Thomas Peter

BEIJING/MELBOURNE (Reuters) - The North American unit of a Chinese customs inspection firm said it would suspend checks on cargoes of scrap metal from the United States for a month from Friday, effectively halting all imports of U.S. scrap.

The suspension comes amid a broad crackdown on pollution in China and stricter regulation around waste imports. It poses a serious headache for China’s scrap buyers: the United States is a major source of scrap metal for China and top supplier of scrap copper.

In a notice to customers dated May 3, reviewed by Reuters, China Certification and Inspection Group (CCIC) North America said it would stop processing applications and issuing certificates for scrap material shipments from May 4 to June 4.

The company could not immediately be reached for comment outside normal working hours in the United States.

The inspection firm said in the notice it would empty every container of U.S.-origin scrap from May 4 to check for plastic and other hazardous waste products, which it would send for further testing.

During the month-long period, CCIC North America “will temporarily stop processing applications and issuing the certificate for pre-shipment inspection on scrap materials to China,” it said.

Last year, China imported a total of 5.74 million tonnes of scrap metal, mainly scrap copper and aluminum, according to official data. But imports have fallen sharply year on year so far in 2018 as quotas have been progressively tightened.

China imported 50,000 tonnes of copper scrap from the U.S. in March and more than 500,000 tonnes last year, equivalent to 15 percent of the country’s secondary supply.