The accident involving a pop-up urinal on Amsterdam’s Leidseplein on Friday may have been caused by a gas explosion, the Parool reports on Monday.

The urinal, which can be lowered into the ground when not needed and elevated at busy periods, blasted a moped into the air when it suddenly shot up. The moped hit the system manager who was nearby, breaking several bones, including eight ribs. He is still in hospital.

‘What gas and how it got into the system is unclear,’ Urlift spokesman Wim Hermans said. The system is powered by an electric motor and not connected to the gas supply, he said.

There are nine so-called ‘urilifts’ in Amsterdam, which are only used at the weekend. Their use has been halted pending the outcome of the investigation. The system was developed in 2000 and there are no reports of any other incidents, the company said.

Urilift has placed some 200 of the pop-up urinals in Dutch cities as well as in Sweden, Britain, Denmark and Belgium.