LUSAKA, Zambia (AP) -- A Chinese-owned mining company has been accused of covering up the extent of a disastrous toxic spill in Zambia that polluted a major river that millions rely on with cyanide and arsenic.

The spill happened in February when part of a dam that held waste from the Sino-Metals Leach Zambia copper mine collapsed, allowing it to flow into the Kafue River that runs through the heart of Zambia. Sino-Metals Leach Zambia is a subsidiary of the state-run China Nonferrous Metal Mining Group.

An environmental cleanup company says that it was contracted by Sino-Metals Leach Zambia to investigate the accident. It said its two-month investigation found that the disaster resulted in the release of 1.5 million tons of toxic material -- at least 30 times more than Sino-Metals admitted at the time.

The South Africa-based environmental company Drizit said it submitted preliminary reports to Sino-Metals "indicating the severity of the pollution," but Sino-Metals then terminated its contract one day before the final report was due.

Sino-Metals said in a statement to The Associated Press that it terminated the contract because of "contractual breaches" by Drizit and the Zambian government was looking for a new company to conduct a fresh investigation. Sino-Metals disputed the accuracy of Drizit's findings.

The accident happened on Feb. 18 at a mine near the northern city of Kitwe, the second biggest city in Zambia and home to around 700,000 people. The city's water supply was temporarily shut down because of the spill.

Toxic waste flowed into waterways that connect to the Kafue River, killing fish at least 100 kilometers (62 miles) downstream. More than half of Zambia's 21 million people rely on the Kafue for drinking water or to irrigate crops.

Zambian President Hakainde Hichilema called for help from experts and described the accident as a crisis. Authorities in the southern African country said the "devastating consequences" included the pollution of the river, the destruction of crops along its banks and the contamination of groundwater.

Sino-Metals Leach Zambia apologized and said they would help with the cleanup. The Zambian government deployed the air force and speedboats to drop hundreds of tons of lime into the river in an attempt to counteract the acid waste and roll back the damage.

The government later said the situation had been brought under control, the water quality was returning to normal, and there was no cause for alarm.

However, the U.S. Embassy in Zambia said last month it was ordering all U.S. government personnel out of the area near the mine because of new information that revealed "hazardous and carcinogenic substances" in the environment.

Drizit claims the toxic spill was much worse than Sino-Metals Leach Zambia and authorities conceded.

Drizit said in a statement that its investigators took more than 3,500 samples for analysis and they showed dangerous levels of cyanide, arsenic, copper, zinc, lead, chromium, cadmium and other pollutants "posing significant long-term health risks, including organ damage, birth defects, and cancer."

It said 900,000 cubic metres of toxic substances were still present in the environment and a proper cleanup operation was required to ensure people aren't at risk for decades. Drizit's full report has not been released publicly.

China is the dominant player in copper mining in Zambia, which is among the world's top 10 copper-producing countries. Chinese investment is key to Zambia's aim to increase its production to three million tons per year by 2031 to match the new demand for copper for use in electric vehicle technology and batteries.

Copper prices have hit record highs this year, while China is the biggest importer of the vital metal.

___

Imray reported from Cape Town, South Africa.

___

AP Africa news: https://apnews.com/hub/africa