Slater and Gordon has been fined £80,000 and issued with a written rebuke by the Solicitors Regulation Authority (SRA), after disclosing confidential information from more than 7,000 client matter files.

The firm has also been ordered to pay the SRA's costs of £26,000 after it was found to have disclosed unredacted confidential information and documents from 7,087 client matter files to other firms.

Half of the £80,000 fine has been issued to Slater & Gordon UK LLP, while the other half will be paid by Slater Gordon Solutions Legal Limited, the company formerly known as Quindell Legal Services Limited. The two businesses will pay the SRA's £26,000 costs between them.

The information was all shared without the knowledge or consent of the relevant clients between December 2014 and February 2015.

Slaters acquired Quindell's professional services division for £637m in 2015, an ill-fated deal which last year culminated in the split-off of the firm's UK business from its Australian parent into a holding company owned by the indebted firm's senior lenders.

A Slaters spokesperson said there was no evidence that client data was released outside of firms regulated by the SRA, adding: "We take our obligations relating to confidentiality extremely seriously."

The spokesperson said: "The Solicitors Regulation Authority carried out a detailed investigation into matters that occurred in 2015, during the Quindell period. It is important to stress the SRA concluded there was no evidence that clients' data was released outside of firms regulated by the SRA.

"However, we accept the SRA's conclusion that a breach took place in relation to the due diligence process during this complex business transaction."

This May, the firm announced its intention to consolidate the two arms of the business – Slater and Gordon Lawyers and Slater Gordon Solutions Legal – into a single alternative businesses structure.

At present, Slater and Gordon's UK LLP, which encompasses the firm's UK legal practice, is separate from Slater Gordon Solutions Legal, which is a personal injury claims service.

Slaters – which in 2007 because the first ever law firm to go public when it listed in Australia – entered the UK market in 2012 with the £53.8m acquisition of Russell Jones & Walker. A flurry of takeovers followed, culminating in the 2015 purchase of Quindell. The firm has been since been plagued by difficulties, with its share price collapsing, and has alleged fraudulent misrepresentation in connection with the deal.