The first illegal ebikes seized under new laws have been crushed in New South Wales as a major Sydney hospital has warned of a spike in trauma injuries driven by those riding under the influence.

The NSW government crushed 23 ebikes at a wrecking yard in western Sydney on Thursday, turning them into scrap metal. NSW police are assessing applications for the return of an additional 13 bikes seized during a joint operation by with Transport for NSW in the northern beaches in September.

The NSW transport minister, John Graham, told reporters onsite on Thursday “this isn’t a scene from Mad Max. This is where illegal ebikes go to die.”Graham said tough news laws were necessary “because of some of the bad behaviour we’ve seen … on our state’s streets, on the golf courses in Sydney suburbs, even on the Sydney harbour bridge”.

On the same day, St Vincent’s hospital released figures that showed a 22% spike in legal and illegal ebike injuries, with 42% of those injuries triggering a trauma response and the majority being injured while riding under the influence of alcohol or drugs, riding too fast or without a helmet.

It found 361 patients presented to the hospital for ebike injuries between January and July, compared with 296 presentations during the same period last year.

Dr Ed Lewis, acting head of rehabilitation medicine, told reporters injuries included fractures, internal bleeding, as well as the “perforation of certain organs”. He said they often included brain injuries from severe head trauma, “as well as milder knocks, like a concussion, which can still have long-term repercussions for patients”.

Lewis told Guardian Australia that those contemplating riding an ebike home while intoxicated “need to have a plan B or a backup solution”.

“The message that we want to say to people is: enjoy using ebikes, but respect what they are. Respect that they are fast. Wear a helmet and just don’t ride impaired.”Graham said the government was concerned by the number of injuries, but it was “important to keep it in context”.

“The number of e-bike injuries is still low compared to cars … but it rising.” he said. “If you’re not wearing a helmet, you are dicing with danger.”He stepped aside to allow a giant metal claw pick up a tangle of ebikes, cracking frames in half and popping tires. They were loaded into a conveyor belt before being crushed and shredded. Graham said batteries had been removed for safe disposal and recycling beforehand.

Under powers which came into effect in August, police and transport officers can seize bikes not restricted to 25km/h, whose maximum speed while not pedalling does not exceed 6km/h, and maximum continuous power of 500 watts, due to reduce to 250 watts in March 2029.

The government says the bikes crushed include one capable of speeds of more than 90km/h seized from a 14-year-old, a food delivery bike, and bikes whose speed restriction settings had been tampered with.

The 36 ebikes seized so far represent a fraction of the estimated 760,000 in the state. The changes were prompted by a surge in injuries and high-profile incidents including one in which in which about 40 ebikes swarmed the Sydney Harbour Bridge in February. An expert review on implementing an age limit of between 12 and 16, was due to report back to the government in June.

The NSW premier, Chris Minns, appearing on the debut of Kyle Sandilands Live in August, said the government was “examining an ... age limit of 12”, but hadn’t finalised the details.

On Tuesday, Graham would not say if the premier had revealed the planned age limit. “I want to discuss this with my colleagues and also with the public,” he said.