DLA Piper is set to be investigated by the Solicitors Regulation Authority (SRA) after emails from partners referring to a former client as a "nutter" have emerged.

The Times reports today that former DLA Roger McCourt sent celebratory emails to colleagues after the firm obtained a bankruptcy order against Sheffield-based property developer Steve Wilkinson, who was previously a client of the firm.

When a bankruptcy order against Wilkinson was obtained in 2009 McCourt – who was acting for Royal Bank of Scotland, a lender to Wilkinson's business, PremiSys, which failed in 2002 – emailed his colleague saying "good news – the wicked witch is dead".

In a separate email exchange in 2008 DLA partner Duncan Mosley responded to news of an earlier judgment against Wilkinson by saying: "I think I'll take a wander up the road for a spa treatment at the Turkish bath suite and see if they stock any champagne to enhance the experience further."

In other emails Mosley also referred to Wilkinson as a "nutter" while DLA's current joint global head of litigation and regulatory, Stephen Sly, said he had a "twisted mind".

Wilkinson reported the firm to the SRA after he acquired the emails following a request for the firm to release data held on him.

In his complaint to the regulator, Wilkinson accused the staff of wrongfully conspiring against him to secure the bankruptcy.

Wilkinson had previously employed DLA for work regarding one of his businesses but was no longer a client of the firm at the time the emails were sent.

Wilkinson told The Times that the emails showed "arrogance and hubris" and he felt that he had been "abused and laughed at" by the firm.

He said: "To have a global law firm… actively wish to celebrate [my] demise by visiting the vanquished premises to quaff champagne is sick."

A DLA spokesperson said the comments "did not reflect the standards or values of the firm or the individuals that made them".

She added: "These comments were made more than six years ago about an individual who, over a period of seven years, heavily contested High Court proceedings involving our client, but ultimately failed and judgment was made against him.

"During this time he also made many disparaging and abusive statements about our personnel. We regret that the frustration caused by such circumstances was reflected in the language used about him in some internal emails between colleagues."

A spokesperson for the SRA said that it was unable to comment on ongoing cases.