A ferry carrying nearly 500 passengers crashed into a wall at an Essex port because a button activating a propulsion back-up system was accidently pressed as the vessel approached land, a report has said.

The finding comes from a document published by the Marine Accident Investigation Branch (MAIB) into what caused the DFDS Sirena Seaways to make “heavy contact” with the quayside at Harwich International Port on June 22 last year.

All 489 passengers on the ferry were left stranded on board for several hours after the ship ran into a hydraulic boarding ramp at Parkeston Quay.

The impact left a hole beneath the waterline on the 23,000-tonne vessel, which had just arrived from Esbjerg in Denmark, and resulted in the ship taking on water and initially listing by five to 10 degrees.

Passengers at the time reported hearing a “bang” and some “metallic noises”, and feeling the ship “judder” as it hit the quayside.

The report said the ship’s records showed that because the back-up button had been pushed the starboard propulsion system remained at around 63% of full capacity throughout the accident and continued to be so for nearly two hours after the crash, hampering attempts to pull the vessel from the damaged berth.

The report added that it was likely the button was pressed by accident when the button next it, which activated the lights for the ferry’s control console, was pushed.

“The starboard CPP back-up control button was positioned closely to the ‘lights up’ button and it was not fitted with a protective cover. Given the time at which it was activated, it was most likely that it was pressed inadvertently as the brightness of the centre console indicator lamps was increased,” the report stated.

It also found that no warning was given to the passengers and crew, other than the mooring teams, before the impact and that while engineers in the engine control room of the ferry noticed the back-up system indicator lamp was lit they did not attempt to clarify with the team at the ship’s bridge why it had been operated.

“Complacency in communications between the teams led to a breakdown in the shared situational awareness of the vessel’s propulsion system and indicates the crew were not working as a cohesive team,” said the report.

It recommended that DFDS “review the need for regular bridge and crew resource management training” and “consider methods for warning passengers and minimising the risk of injury in a similar emergency.”

In response, a spokesman for DFDS said: “Safety is of paramount importance to DFDS Seaways and we work hard to continually develop our safety standards.

“We will therefore use the information from this incident to see how we can reduce the risk of similar incidents in the future, and will also use the report and its recommendations to review our training procedures.”