SINGAPORE - A Singaporean couple still unaccounted for days after a 7.4-magnitude quake struck Taiwan were last seen alighting from a bus at the Shakadang Trail in Hualien’s Taroko Gorge, according to the vehicle’s CCTV footage.

A grainy 14-second clip shows the couple, Mr Sim Hwee Kok and Ms Neo Siew Choo, getting off Taroko Gorge tour bus 310 at 7.20am on April 3. About 40 minutes later, the worst earthquake in 25 years struck the island.

Hualien was the hardest hit as the epicentre was about 18km south-west of the city on the east coast.

Rescuers are trying to determine the likely areas where Mr Sim and Ms Neo could have walked to within 40 minutes, the Taiwan quake relief authority said in a statement on April 7. A Turkish team equipped with drones is among the rescuers racing to look for survivors in the area.

The couple, who reportedly also hold Australian passports, boarded the bus at around 6.30am on April 3 but got off before the terminal station. The authorities were previously unable to retrieve the CCTV footage from the bus as communication services were down.

Dual citizenship is prohibited in Singapore. It is unclear why the couple have two passports.

As at 9am on April 7, there were 13 deaths, 1,133 people injured and six people missing after the earthquake.

The Singapore Trade Office in Taipei is in touch with the local authorities on the matter, and its officials have been in contact with the next of kin and are providing consular assistance.