A 6.3-magnitude earthquake struck off the coast of Taiwan on Monday, according to the US Geological Survey, swaying high-rise buildings and delaying train services.

The offshore quake hit just before 2:30 pm (0630 GMT) at a depth of 27 kilometres (17 miles), according to the USGS.

It was centred about 70 kilometres southwest of Yonakuni, a Japanese island not far from Taiwan.

Taiwan's Central Weather Bureau said the shake, the fifth this year above a magnitude of 6.0, was felt across the island, though there were no immediate reports of damage.

It was followed by two aftershocks with magnitudes of 5.4 and 5.2 within 90 minutes of the initial tremor, the weather bureau said.

On average, Taiwan clocks two to three tremors of 6.0-magnitude or higher a year, according to the bureau.

Taiwan Railways Administration said 17 trains were temporarily running at reduced speed as a precaution after the earthquake.

"Hope everyone is safe... there could be some aftershocks and please be cautious," New Taipei City Mayor Hou You-yi posted on Facebook.

The Japan Meteorological Agency, which estimated the tremor as a 6.6-magnitude, said it may prompt minor sea-level fluctuations, but has not issued a tsunami warning.

Some Taiwanese social media users posted photos comforting their scared pets or of lights shaking in their buildings.

"(My building) was shaking like a pendulum," actress Ada Pan said in a Facebook post.

Taiwan and the surrounding area are regularly hit by earthquakes due to the nearby junction of two tectonic plates. 

In March, a 6.7-magnitude earthquake that struck off Taiwan's eastern coast rattled buildings and roused people from sleep, leaving one injured and collapsing a half-constructed bridge in the island's east.