Environmental authorities in east China's Shandong Province said Thursday that they have not found evidence that a local factory has disposed of polluted water underground.

Xie Zhenxi, an official from the environmental supervision and inspection department of the city of Weifang, said investigators checked a factory owned by Weifang Xianda Chemical Co., Ltd. and did not find any wells containing polluted water.

The investigators found that the factory delivered 32,200 cubic meters of waste water to a nearby sewage treatment plant last year, even more than the estimated amount calculated in an environmental appraisal report, Xie said.

The investigation was conducted in response to an online post written on Monday in which a netizen accused the company of digging three wells to dispose of polluted water.

Another post written on Feb. 11 claimed that many local enterprises have disposed of waste water underground, thus polluting the local water supply.

Following the claims, the municipal government offered a 100,000-yuan (15,873 U.S. dollars) reward to the first person to offer information to prove the claims.

Fourteen cases of illegal dumping had been identified as of Tuesday, although no wells have been found.

Further inspections will be carried out and penalties will be given to companies that dump waste water underground, Xie said.

The online posts come amid other claims that underground water supplies in China's urban areas are heavily polluted, although experts have questioned the accuracy of the claims.

Zhang Jian, deputy chief of the environmental science and engineering school of Shandong University, questioned worrisome data quoted online stating that 64 percent of the underground water in China's urban areas is polluted.

"The truth is that our country has yet to conduct a survey for underground water quality," said Zhang, calling on government departments to carry out such studies and release authoritative figures to the public.