A Chinese seismologist on Wednesday refuted claims on the Internet that the authorities covered up predictions of the devastating southwest China earthquake to avoid panic ahead of the Beijing Olympic Games.

Earthquake forecasts should be based on scientific analysis, and not tailored to political requirements, said Zhang Guomin, a research fellow with Institute of Earthquake Science under China Earthquake Administration.

Zhang's comments came as the country's seismological authorities sought to diffuse public concern over earthquake forecasts.

Zhang said no seismological authorities in any country could accurately predict earthquakes.

He said the limited knowledge of earthquake activity, the seismological complexities, the inaccessibility of the tectonic plates and the rarity of earthquakes made predictions difficult.

After the earthquake on Monday, many Internet users questioned the seismological department's competence to predict such disasters, which is considered by most Chinese seismologists as impossible.

Many Internet users have claimed that a photo, allegedly taken in southwest China's Chongqing municipality, of thousands of frogs crossing a road was evidence of an impending disaster.

In a forum on bbs.artron.net, a writer named "Alun" posted the picture on Monday under the caption: "This is a picture taken by a netizen when the earthquake took place. Should the frogs do the forecasts instead of the seismologists?"

Other allegations of a cover-up have focused on an alleged screen snatch of the Sichuan provincial government website on May 9, in which the Aba prefectural authorities had published a notice denying predictions of an earthquake in Maerkang county and urging public calm.

A blogger named "Piaoyangguohai" posted the screen snatch on spaces.live.com to highlight the notice in which village leaders are alleged to have mistakenly used the words "di zhen zai hai" (earthquake disasters) instead of the intended "di zhi zai hai" (geological disasters).

Zhang Xiaodong, deputy director of China Earthquake Networks Center, said, "I feel deeply regretful and sorrowful at the failure to predict the earthquake."