Workers have walked off site after man was fatally crushed in a scissor lift at the new Royal Adelaide Hospital site on the weekend.

Sixty-three-year-old Steve Wyatt died after being crushed between a doorway and the scissor lift’s handrail, which was reportedly being operated by another worker.

Union officials met with mourning workers after the incident, before most went home for the day. They are expected to return to the site on Monday or Tuesday.

It is not the first such fatal accident at the Royal Adelaide project, after 54-year-old Jorge Castillo-Riffo was crushed between a scissor lift and a concrete slab in 2014.

The CFMEU, which represents the workers, says scissor lifts will not be used at the site until further notice.

SafeWork SA investigators were on site on Monday, while workers have been offered counselling services.

CFMEU secretary Aaron Cartledge said many workers felt under pressure.

“They're pushed very hard at the moment to achieve a deadline and whenever you're pushed hard like that you increase the amount of activities, the amount of workers, the amount of things going on on site,” he said.

“And hours get longer, fatigue sets in, so any of those factors could have caused this.”

The major proponent of the joint venture building project, Hansen Yuncken Leighton Contractors, has expressed its sympathies to Mr Wyatt's family, but has not answered any further questions.

SA Health Minister Jack Snelling said there was “no big rush” for the hospital to be completed even though it is behind schedule.

The builders maintain it is on time.

“If they don't believe they can meet their current timelines safely then they need to come to the Government to negotiate an alternative delivery date,” Mr Snelling said.