Risks to China's economy could drag 2014 GDP to its lowest level since 1990 before stimuli from structural reforms start to have an effect, economists say.

Qu Hongbin, chief economist in China at the British bank HSBC, expressed his concerns on Tuesday in Beijing about a further slowdown of the world's second-largest economy, as reform plans raised by the Third Plenum of the 18th Central Committee of the Communist of China in November could be slow to show results.

He forecast that the GDP may increase by about 7.7 percent this year or even as little as 7.5 percent, which would be China's slowest annual growth since 1990.