A magnitude five earthquake struck off the coast of southeastern China early on Monday, but no injuries were reported.

Authorities said the quake hit at 3.20am off the coast of Nan'ao county in Shantou city, about 350 kilometres east-northeast of Hong Kong.

The Hong Kong Observatory said it had received several reports of people feeling minor shaking for a few seconds.

"Initial estimate gave a local intensity of three on the Modified Mercalli Intensity Scale, that is felt indoors. Vibration like passing of light trucks," the observatory said.