Specialists said Wednesday there is no evidence to support the hypothesis that the Three Gorges Dam, the world's largest water conservation project, is to blame for the severe drought currently plaguing central China.

"With the current observation devices and data, we have found no evidence that the drought was caused by the dam," said Liu Min, a meteorological specialist with the Hubei Provincial Weather Bureau.

Judging from data collected before and after the dam was built, Liu said it had "very little" impact on the regional temperature, humidity, wind velocity and other climate conditions.

In their report on the Three Gorges Dam's impact on the local environment, Liu and his colleagues concluded the impact was less than 10 kilometers.

"So we believe the ongoing drought is more a periodical phenomenon than a result of improper water conservation," Liu said.

The worst drought to hit the middle and lower reaches of the Yangtze River in 50 years has affected 9.89 million people in four central provinces, including Hunan, Hubei, Jiangxi and Anhui.

Some Internet users have blamed the dam.

"The dam has blocked water from flowing downstream -- that certainly causes climate changes," said a Beijinger who gave his screen name as "Bull village head."

Extreme weather conditions in recent years, including last year's prolonged drought in southwest China and torrential rainfall in the central provinces, have almost always triggered public suspicion over the dam.

Zheng Shouren, an academician with the Chinese Academy of Engineering and one of the dam's chief designers, dismissed such blame and suspicion as groundless and unfair. "Had there not been the dam, the drought would have worsened in the middle and lower reaches of the Yangtze."

The dam, he said, was designed to store water toward the end of the Yangtze's flood season and supply water to the middle and lower reaches in the dry season. "During the dry season from January to May, water supplies from the dam reservoir exceeded Yangtze's natural water flow to the downstream by 2,000 cubic meters."

The Three Gorges Dam was launched in 1993 with a budget of 180 billion yuan (22.5 billion U.S. dollars).

Located on the middle reaches of the Yangtze River in Hubei Province, the total project consists of a 185-meter-high dam, which was completed in early 2006, a five-tier ship lock, the reservoir, and 26 hydropower turbo-generators.

The project generates electricity, controls flooding by providing storage space and adjusts shipping capacity.