At least 11 people have died and hundreds more were injured after a powerful earthquake struck southern Taiwan.

Around 340 people were rescued from the rubble in the city of Tainan after a high-rise building collapsed following the 6.4-magnitude quake.

About 2,000 firefighters and soldiers scrambled with ladders, cranes and other equipment to the ruins of the 17-storey residential building.

It is unclear how many people were missing. Local media reports, citing families and friends, said more than 100 people are unaccounted for, but local authorities were unable to confirm the figures.

Local media said the building included a care centre for newborns and mothers, with an infant among the dead in the disaster, which came two days ahead of the Lunar New Year celebrations.

Most people were still asleep when the quake struck at about 4am local time. It hit some 22 miles south-east of Yujing, and struck about six miles underground, according to the US Geological Survey.

Taiwan's emergency management information centre said 11 people were killed, including nine who were found at the ruins of the fallen building. It said 475 people were injured, with 368 of them discharged later from hospitals.

Rescuers found the bodies of a 10-day-old infant, two young girls and six adults at the collapsed building. Authorities said two other people were killed by falling objects elsewhere in Tainan, which was worst-hit by the tremor.

Rescuers pulled out 248 survivors from the building, the emergency management information centre said. Throughout Tainan, 337 people were rescued, the city government said.

Dozens more people have been rescued or safely evacuated from a market and a seven-floor building that was badly damaged, the official China Central News Agency reported. A bank building also careened, but no injuries were reported.

As dawn broke, live Taiwanese TV showed survivors being brought from the high-rise, including an elderly woman in a neck brace and others wrapped in blankets. All told, nine buildings collapsed and five careened in Tainan, officials said.

The disaster response centre said 1,236 rescuers were deployed, including 840 from the army, along with six helicopters and 23 rescue dogs.

The quake was felt as a lengthy, rolling shake in the capital, Taipei, on the other side of the island. But Taipei was quiet, with no sense of emergency or obvious damage just before dawn.

Residents in mainland China also reported that the tremor was felt there.

Questions are being asked if the construction crew had cut corners when building the Wei Guan residential complex, which was finished in 1989. The interior minister, Chen Wei-zen, said an investigation would examine if the developer skirted requirements.

Earthquakes frequently rattle Taiwan, but most are minor and cause little or no damage.

However, a magnitude-7.6 earthquake in central Taiwan in 1999 killed more than 2,300 people.