Daniel Doctoroff, the CEO and president of Bloomberg LP, has posted his first blog on the company's web site apologizing to customers and reassuring them that the firm is available to answer concerns following last week's disclosure that Bloomberg reporters accessed information on clients' accounts, including which functions they had used.
"Since the news came out, my executive team and I have personally reached out to more than 300 clients," Doctoroff wrote.
"We've listened carefully and also explained the very specific and limited nature of the data our reporters were able to access. We've reiterated what data was available, how it was used, and just as importantly, what was not accessible, including messaging, trading, portfolio, monitor, blotter and other related systems. We're grateful for the understanding our clients have shown."
The issue was revealed after Goldman Sachs complained about a Bloomberg News reporter using terminal logon information to enquire whether an employee had left the bank.
Last week, Doctoroff sent a note acknowledging that Bloomberg had made a mistake in allowing journalists access to limited high-level client relationship data and said Bloomberg would limit reporter access to only the information available publicly to all terminal users. The company has also created a new post of a client data compliance officer.
"We will do everything possible to ensure the integrity and confidentiality of our clients' data in all situations and at all times. We are available to all of our 315,000 subscribers to answer any questions or concerns," he said.
CNBC has learned that the Federal Reserve, the U.S. Treasury Department are examining the extent to which Bloomberg-terminal usage by top officials may have been tracked by Bloomberg's journalists. On Monday, the Bundesbank and the European Central Bank also said they were in close contact with Bloomberg LP over the data breach.
(Read More: Wall Street: How Much Does Bloomberg Know?)
"The ECB takes the protection of confidentiality in the usage of data products by ECB management and staff very seriously," it said.
Meanwhile the Bundesbank released a statement indicating that it had no knowledge of whether the personal user data of members of staff had been mined by Bloomberg journalists.
"We are analyzing the situation and are in contact with Bloomberg. We do not comment on the use of news terminals by members of the Deutsche Bundesbank's Executive Board," it said.
On Monday, the Financial Times reported that more than 10,000 private messages sent between users of Bloomberg's financial terminals were put online and freely available for anyone to browse. Two lists of confidential Bloomberg messages between traders and their clients have been online for several years, it said.
But, Aaron Kwittken, the CEO of communications company KCO said Bloomberg had taken the right steps after the revelations, making top officials accessible and apologizing.
(Read More: Fed, Treasury Examining Bloomberg Use of Data)
"Bloomberg, once revered for being an unimpeachable first-class news operation is actually fallible like its peers. Unlike its peers (for example News Corp), however, Bloomberg executed their response to this near flawlessly and it deserves props," he said in a note to CNBC.
"But, what took them so long...they knew about this in 2011 and could have gotten out ahead of it."
Kwittken added that the question now is whether Bloomberg should consider spinning off its news division away from the unit that deals with the data terminals
"Is the 'wall' between them really just a 'fence'. Should Thomson Reuters consider the same? What about Dow Jones?," he said
—By CNBC.com's Matt Clinch; Follow him on Twitter