Chinese scientists have said that the migration of toads or unusual cloud formations cannot be the true indicators of earthquakes.
Zhang Guomin, a senior researcher at the China Earthquake Administration, said on the government's website that predictions cannot simply be based on the movement of animals.
Media reports blamed the forecasters for ignoring the warning signs, such as the mass migration of toads in Mianzhu, just three days before the earthquake happened, Xinhua reported.
Zhang Xiaodong, a scientist with the China Earthquake Networks Center, said it is difficult to predict earthquakes because they often take place deep underground where detection equipment cannot be placed.
Earthquake's occurrence depends on the surrounding geological structure, which makes it difficult to obtain meaningful samples to analyse, he added.
"Studies by Chinese scientists have yet to reach a definite conclusion on whether the abnormal behaviour of animals is a result of environmental conditions, climate change or an earthquake," Xiaodong said.
Deputy Director of the China Earthquake Administration, Xiu Jigang, said cloud formations frequently change and therefore are not reliable in predicting tremors. Earthquake forecasting is based on strict scientific analysis.