Liangzhou district government on Monday denied a report saying that in cleaning up a polluted desert, the material, including sewage and sludge, were covered up instead of removed.

Ronghua Industry & Trade Co in Wuwei, Gansu province, illegally discharged more than 83,000 metric tons of untreated sewage into a pit in the Tengger Desert between May of last year and March, contaminating about 18 hectares, the district government said on March 21.

It also said the wastewater should be collected and processed in sewage treatment plants, with some sludge and water left in the bottom for experts to research.

But a report from Changjiang Times on Monday said that after visits by one of its reporters to the polluted area of the Tengger Desert, some of the remaining material had been buried by the company. And the reporter who went to the polluted desert was detained for nine hours by company officials.

The Liangzhou district government of Wuwei, where the company and the polluted desert are located, later Monday denied the company buried the polluted material. The announcement was posted on its official website on Tuesday.

It said some of the sludge and sewage were left in the pit to wait for further tests and solutions from experts and the company did not cover up the polluted sludge and sewage with sand.

Also, the reporter did not provide a press card, to prove his identity as a reporter and there was no such information on the official website in charge of journalists, so a police officer from the district police security bureau and the company checked his information, but did not detain him, the company said.