Police and fire services investigators have been on the site for over a week, using dogs trained to sniff out whether accelerants were used at the building site.

Notts Police said: “We have concluded our examination of the site, which is now subject to the Health and Safety Executive, but our investigation continues into establishing the cause of the fire.”

The HSE said it was now looking into the cause of the fire at the £20m timber-framed building, which was being built by Morgan Sindall and was at the fit-out stage.

Sixty fire fighters and 10 engines battled to bring the fierce blaze under control, when the alarm was raised earlier this month.

But the building was quickly engulfed and completely destroyed.

The project was part funded by GlaxoSmithKlein and was billed to be the world’s first zero carbon chemistry laboratory.

An HSE spokesperson told the Nottingham Post: “The HSE is working with police and fire services to investigate the cause of the fire at the Nottingham University campus.

“HSE’s involvement will be to establish whether the fire was caused by unsafe working practices on a construction site, and to consider adequacy of the fire precautions in place.”

A spokesperson for Morgan Sindall said: “The Health and Safety Executive are undertaking a routine, statutory role in investigating the recent fire at The University of Nottingham.

“The cause of the fire remains under investigation and no cause has been ruled in or out at this stage. We remain committed to assisting the investigation into the fire in whatever way we can.”