A municipal government in east China's Shandong Province has offered a huge reward for clues or evidence of local enterprises pumping emissions underground.

The government of Weifang City has offered a 100,000 yuan (15,873 U.S. dollars) reward to the first whistleblower who can help prove the widely circulated rumors.

On the Twitter-like Sina Weibo microblogging service, users have posted that some enterprises in Weifang like chemical plants and paper mills have been pumping polluted water some 1,000 meters below ground.

The posts, forwarded by Deng Fei, a reporter with Phoenix Weekly, quickly went viral, sparking concerns that China's underground water might have been polluted by unscrupulous enterprises.

The government of Weifang said it has sent more than 600 law enforcement officers to conduct investigations among 715 local enterprises, but they have found no evidence to support Internet users' allegations.

The Environmental Protection Department of Shandong on Sunday also said it found no such evidence after days of secret investigations.

The department said it would soon kick off a campaign in the province to crack down on illegal underground emissions.

Further investigation into the case is underway, the department added.