Image caption Bloomberg journalists tried to glean information from tracking client activities on Bloomberg terminals

News agency Bloomberg has said it was an "inexcusable" error to allow its reporters to monitor the activities of clients on its terminals.

The firm came under fire after it was revealed that Goldman Sachs had made a complaint about journalists trying to glean information from the data.

Now the Federal Reserve is looking into whether its chairman, Ben Bernanke, was also tracked.

Bloomberg says it has now switched off its journalists' access to the data.

Bloomberg editor-in-chief Matthew Winkler apologised in a blog post, entitled "Holding Ourselves Accountable", on Monday.

Editor's apology

"We are defined by our words - and they applied to us when a Bloomberg LP customer expressed concern that Bloomberg News reporters had access to limited client information. Our client is right," Mr Winkler said.

Analysis The heart of Bloomberg's business is providing financial data. That is where it makes its money. The terminals you'll find on any trader's desk account for the bulk of its revenue and it has 315,000 subscribers around the world. So it won't want its expanding news division to threaten the main source of its profits. And that is the risk here. At least it appears Bloomberg's management think so judging by their very public apology. The company has admitted it made a mistake and has created a new position to oversee data security issues. Management want to make sure that the line between its news and business operations isn't crossed again.

"Our reporters should not have access to any data considered proprietary. I am sorry they did. The error is inexcusable.

"Last month, we immediately changed our policy so that reporters now have no greater access to information than our customers have. Removing this access will have no effect on Bloomberg newsgathering."

Earlier, in a memo to staff on Friday, Bloomberg chief executive Daniel Doctoroff had said that while the company had "long made limited customer relationship data available to our journalists... we realise this was a mistake".

Goldman Sachs became worried after a reporter investigating the possible departure of a Goldman employee told the securities firm that the person had not logged into a Bloomberg terminal for weeks.

JP Morgan reportedly was also targeted, according to the Associated Press.

A person close to the matter was quoted by AP as saying that a number of Bloomberg reporters had used the data to try to score scoops, including finding out whether disciplinary action had been taken against Bruno Iksil, a JP Morgan trader nicknamed the London Whale, who was accused of a $6bn trading loss last year.

JP Morgan reportedly complained to Bloomberg, but the media firm said it was not aware of a formal complaint.

Separately, a Bloomberg spokesperson said the Federal Reserve had also contacted Bloomberg to see whether journalists monitored terminal activity by Fed Chairman Ben Bernanke and former Treasury Secretary Timothy Geithner.

The European Central Bank (ECB) said it had also been in touch with Bloomberg.

"The ECB takes the protection of confidentiality in the usage of data products by ECB management and staff very seriously," an ECB spokesman told Reuters. "Our experts are in close contact with Bloomberg."

'Function' views

Until recently, Bloomberg reporters could see when any of the company's paid subscribers - numbering more than 300,000 - last logged into the terminal, as well as what "functions" they were viewing.

Reporters could see whether clients, including many stock and bond traders, looked up news stories or data, although not the content of the information.

Reporters could also see if subscribers were using "message" or "chat" functions to send messages to each other over the terminals, but not their content.

In his staff memo, Mr Doctoroff said reporters did not have access to "trading, portfolio, monitor, blotter or other related systems or our clients' messages".

Reporters were mostly getting contact information for subscribers, such as telephone numbers and email addresses, he said.

No journalists have been fired over the matter, but senior executive Steve Ross has been appointed to oversee client data compliance to review Bloomberg's policies, the company said.