A construction worker has died on the site of the new Queensferry Crossing after reportedly being struck by part of a crane.

Another worker suffered minor injuries in the incident on the north tower deck at about midday on Thursday. The new £1.4bn road bridge is set to open in December and will carry the M90 across the Firth of Forth between South Queensferry, near Edinburgh, and North Queensferry, in Fife.

Work on the site has stopped while the death of the 60-year-old man is investigated. The construction workers’ union Ucatt said it is understood the man was struck by the boom of a crane he was directing.

Union leaders said the death on Workers’ Memorial Day was a poignant reminder of the dangers in the construction industry. Work on the bridge started in 2011 and the death is thought to be the first at the site.

A spokesman for the project said: “We are deeply saddened to have to confirm there was an incident just before noon on April 28 on the Queensferry Crossing’s north tower in which a person has lost his life.

“One other person has been taken to hospital. All activity has been stopped at the north tower. Our thoughts are with the family and friends of our colleague and co-worker at this time.”

Ucatt regional secretary Harry Frew said: “Ucatt sends its sincere condolences to the family of the worker who has suffered this tragic accident. It is impossible to imagine how they must be feeling.

“Ucatt will be doing everything it can to find out how and why this accident occurred, and to ensure that similar fatalities are prevented in the future.”

A Police Scotland spokesman said the force received a call at about 12.20pm on Thursday. “Sadly, the man was pronounced dead a short time later. Another man on the bridge also sustained minor injuries. Inquiries to establish the full circumstances surrounding this matter are ongoing.”

Pat Rafferty, Unite’s Scottish secretary, said: “Our thoughts are with the deceased’s family to whom we offer our profound condolences. Once again, a loved one has gone to work and will not return home. That is hard to swallow any day but on today of all days, on International Workers’ Memorial Day, when we remember those who have perished at work, this loss is especially poignant.

“We call on the Scottish Health and Safety Executive to thoroughly investigate what has happened here.”