The UK Financial Conduct Authority (FCA) has opened an investigation into the massive Equifax data breach that exposed the personal information of almost 700,000 British citizens and 145.5 million worldwide.

The FCA's inquiry joins one already underway by the UK's Information Commissioners Office, Bloomberg News reported, along with those being run by the U.S. Federal Trade Commission, the House of Representatives' Oversight Committee, several state attorneys and the Consumer Financial Protection Bureau.

Nicky Morgan, chair of the House of Commons Treasury Committee, has informed Patrico Remon, president of Equifax Europe, that he may be called to testify before his committee, Bloomberg reported.

Since news of the Equifax data breach broke in September the company's CEO, CTO and CSO all retired. The attackers exploited a vulnerability in open-source server software Apache Struts used by Equifax.