KPMG has forced out the head of one of its core businesses in Britain after an investigation into his conduct involving messages sent on WhatsApp.

Tim Howarth, head of UK financial services consulting at KPMG, is the third senior partner to be investigated by the firm this year over claims of misconduct.

KPMG convened a disciplinary panel on Friday and then ousted Mr Howarth, whose profile was removed from the firm’s website over the weekend. Two people briefed on the matter said it related to messages sent via the WhatsApp service.

Mr Howarth, 53, worked at KPMG for 15 years and was the lead partner for one of the firm’s largest clients, Lloyds Banking Group. He also ran KPMG’s risk consulting practice.

KPMG said: “We hold all of our people to a very high standard and take swift and appropriate action against any individual whose behaviour contravenes the firm’s values. As part of this commitment, we can confirm conduct issues have been raised related to a partner and, following an internal investigation and disciplinary panel, that partner has left the firm. Under our process the partner has appealed.”

Mr Howarth said: “I am surprised by the KPMG announcement of the outcome of a disciplinary panel, which is bizarre as the decision is under appeal. I have not been given the reason for that decision. I had already resigned from the KPMG partnership. I did not believe that the process was fair or would lead to a just outcome. There is no complainant and there were no formal allegations pursued by anyone.”

Prior to joining KPMG, Mr Howarth worked at the Financial Services Authority, Britain’s industry regulator, for eight years in various policy roles.

KPMG’s financial services work, including consulting and audit, generated revenues of £681m last year, making it one of the firm’s largest business lines. KPMG’s risk consulting unit advises company boards on managing risks such as fraud and financial crime, regulatory compliance, cyber attacks and corporate governance.

The dismissal of Mr Howarth comes as KPMG has been battling to restore its reputation following a series of unrelated scandals involving its business and individual employees.

It was involved in a corruption scandal in South Africa and has been scrutinised by regulators and politicians in the UK over the collapse of Carillion, the government outsourcer, which it had audited since 1999. In the US, KPMG was fined $50m by the Securities and Exchange Commission in June, a record fine for an auditor, after its former employees were alleged to have stolen regulatory information.

In January, Peter Meehan, KPMG’s lead audit partner on Carillion, was suspended by the firm. KPMG and the Financial Reporting Council, the audit watchdog, are investigating whether Mr Meehan and his team may have provided documents to the regulator that were backdated in relation to Carillion.

In June, Sanjay Thakkar, head of KPMG’s deal advisory unit, took a leave of absence after two female KPMG partners resigned in protest over how an internal review into allegations of bullying had been handled. The firm has launched a second review into his conduct amid fresh allegations. He has since stepped down from his role.