M&D Leisure – the owner of M&D’s theme park in Motherwell, Scotland – has been fined over an incident that saw one of its roller coasters derailed, injuring 11 people.

The incident, which occurred in June 2016, caused nine children and two adults to be hospitalised and happened on the park's Tsunami ride.

Five carriages on the Pinfari-manufactured ride came off their tracks, plunging roughly 20ft (6m) to the ground and hitting the top of a child’s car ride, before coming to a rest upside down, leaving riders trapped.

UK safety body the Health and Safety Executive (HSE) led an investigation into the matter and has found that the coaster was not maintained properly, nor was it in efficient working order and that weld repairs carried out on its axels were inadequate and unsound.

M&D Leisure pleaded guilty to breaching Regulation 5(1) of the Provision and Use of Work Equipment Regulations 1998 and has been fined £65,000 (US$86,000, €76,000) as a result.

"This was a serious incident that resulted in members of the public being badly injured while they were supposed to be enjoying themselves," said HSE inspector Martin McMahon.

"Our investigation found the company failed to ensure the Tsunami roller coaster was properly maintained and the result of these poor maintenance procedures led directly to its catastrophic failure on 26 June 2016.

"It's imperative that all controllers of fairground rides have thorough maintenance procedures in place to ensure that the public is safe when it enjoys the thrills at a fair or theme park."