An Eastern European crime group is under investigation for using a steel firm to staff the construction site of the new Aberdeen Exhibition and Conference Centre (AECC) with illegal workers, The Press and Journal has reported.

The details of a UK government investigation into Kupa Steelfixing Ltd were revealed last week at Aberdeen Sheriff Court, where Rebani Kupa, 35, admitted his involvement in the operation.

The development of the 12,500-seat venue was contracted to Robertson, who sub-contracted Careys for elements of the work, and Careys in turn employed Kupa Steelfixing Ltd.

The court heard Home Office officials visited the Bucksburn construction site amid an investigation into the Albanian organised crime syndicate understood to be behind Kupa Steelfixing.

A Home Office spokesman later confirmed that six other Albanian nationals had been detained as a result of the inquiry.

Fiscal Alan Townsend, said: “A Home Office investigation team commenced an operation into an Albanian crime group last February.

“It focussed on Kupa Steelfixing Ltd, a firm which had been sub-contracted onto numerous large-scale construction sites.

“The investigation showed that many people employed by the company used false names and identification documents, under the pretence they were born in Kosova.

“A number of Albanian nationals were ultimately arrested for illegally being in the UK.”

A Careys spokesman insisted the company “completely distances itself from organised crime” and had performed all “due diligence” before appointing the steel firm.

He said: “We don’t work outside employment laws, and understood that this individual was permitted to work in the UK.”

A manager for Kupa Steelfixing Ltd, who did not want to be named, strenuously denied that the firm has any connection to organised crime.

He said: “I am aware that Rebani has been detained, but I am not aware of any wider investigation.

“We are still working on the AECC and have done nothing wrong.

“The men who were detained were sub-contractors, not employees, and we did our best to check their documentation.

“We have always been very careful, but have now taken extra steps to stop something like this happening again.

“It is not true that we are associated with organised crime, not at all.”

A spokeswoman for Robertson said the construction group has pledged to assist with the investigation.

She added: “This is an issue for Careys and their sub-contractor. However, we are aware of the investigation and will continue to do all we can to support the Home Office.”

Sheriff William Summers deferred sentence on Kupa until February 28.