Merlin Entertainments’ chief executive, Nick Varney, has said Alton Towers will remain closed until the cause of the Smiler accident that left 16 people injured has been determined.

Following the incident on tuesday, in which a carriage of the park’s £18m (US$27.7m, €24.4m) Smiler rollercoaster crashed into an empty carriage on the track, seriously injuring four people, Varney said the park would only reopen once a thorough investigation into the incident had been concluded.

"At this point I don't know if it was a technological or a human error,” said Varney writing in The Sun.

"We want to know if this issue is isolated to The Smiler. We can't open again until we're sure."

The riders involved in the accident were left trapped 25ft (7.6m) in the air at an angle of 45 degrees for up to four-and-a-half hours, while rescue crews built a platform to reach them.

Two men aged 27 and 18 and two females aged 19 and 17 suffered serious leg injuries in the accident and were taken by air ambulance to major trauma centres. The other 12 occupants also required medical treatment, including a man in his 20s who suffered neck and abdominal injuries.