A Scots drilling firm is to pay back more than £5 million to the state under proceeds of crime law after admitting it gained from corrupt payments made in connection with a business deal.

In the first legal case of its kind, Abbot Group admitted it benefited from a payment made by one of its overseas subsidiaries to an oil and gas company after a contract had been signed between the two. The location of the oil and gas company has not been disclosed for legal reasons.

The improper transaction was brought to light following a query from an overseas tax authority, which prompted Aberdeen-based Abbot to launch its own investigation. The findings were reported to the Crown Office earlier in July.

The Crown Office announced yesterday Abbot will pay back £5.6m in three instalments by March 2015 under proceeds of crime rules in the first civil settlement since a self-reporting initiative was introduced last year.

Abbot said it was deeply disappointed about what took place, with none of the people involved still with the group.

No criminal charges have been brought in connection with the payments.

Solicitor General Lesley Thomson QC said: "Bribery and corruption cause worldwide damage to business and economic development. The self-reporting initiative creates a mechanism for businesses to recognise their corporate responsibility and take a rigorous approach to the investigation and elimination of such practices.

"While consideration must first be given to prosecution of appropriate cases, I am pleased that the Crown Office and Procurator Fiscal Service and the Civil Recovery Unit are committed to taking effective steps to ensure that businesses face up to their responsibilities and relinquish any unlawfully obtained profits."

The contract between the Abbot subsidiary and the oil and gas company was signed in 2006, with the corrupt payments made in 2007.

Louise Andrew, general counsel at Abbot Group, said: "Abbot Group has self-reported to the Scottish Crown Office and Procurator Fiscal Service that it uncovered that, in 2007, improper payments were paid in connection with an overseas transaction. The payments were made to an overseas company. The self-report has led to today's civil settlement agreement with the Civil Recovery Unit in the sum of £5.6m which represents the profit on the contract.

"We believe in conducting business legally and ethically and do not tolerate bribery in any form.

"The Crown Office applies very strict criteria in determining whether a case is suitable for a civil settlement. Civil settlement is only offered if the Crown Office is satisfied that the company operates transparently, has sound anti-bribery systems in place and is fully committed to compliance.

"KCA Deutag (the trading name of Abbot Group Ltd) is committed to anti-bribery compliance and creating a corporate culture in which bribery has no place. The board of directors believe that self-reporting was the right thing to do and demonstrates an absolute commitment to acting legally, ethically and transparently."