The Financial Conduct Authority has admitted to accidentally revealing personal information of about 1,600 people who complained about it, in an embarrassing lapse for the regulator of Britain’s banks and investors.

The FCA published names, addresses and phone numbers in a document on its website, in response to a request for data under the Freedom of Information Act.

The response related to the number and nature of new complaints made against the FCA between 2 January 2018 and 17 July 2019. More than half of the 1,600 complainants had only their names revealed. The FCA said it would write to those who had their addresses and phone numbers revealed to inform them of the breach.

The personal data, which was published in November, were revealed within descriptions of complaints. No financial, payment card, passport or other identity information was included, the FCA said.

The FCA said it had referred itself to the Information Commissioner’s Office, which regulates the use of data, over the breach.

The data breach is particularly embarrassing for the FCA, which fined Tesco Bank £16.4m in 2018 for failing to protect customer information. The FCA was also left red-faced last month when the pensions regulator fined it £2,000 for not being detailed enough with fees charged by investment managers in its staff pension scheme.

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The FCA is one of the most powerful regulators in the UK. It is currently carrying out an investigation into a security breach at the Bank of England. The FCA chief executive, Andrew Bailey, has promised to recuse himself from the investigation before he becomes governor of the Bank on 15 March.

“The publication of this information was a mistake by the FCA,” it said in a statement on Tuesday. “As soon as we became aware of this, we removed the relevant data from our website. We have undertaken a full review to identify the extent of any information that may have been accessible. Our primary concern is to ensure the protection and safeguarding of individuals who may be identifiable from the data.”

The FCA has faced a barrage of criticisms in recent years over perceived failings in its handling of scandals such as the collapse of London Capital and Finance, which sold unregulated mini-bonds, and Royal Bank of Scotland’s mistreatment of small business customers.