Data accidentally published on the US Federal Reserve website shows that staff economists at the central bank expect an about 25 basis point increase in interest rates in 2015.
The leaked data, presented to policymakers at their meeting on 16-17 June, includes the economists' projections on economic growth and inflation.
As per the staff projections, the Fed will increase the benchmark interest rates to 0.35% by the end of the fourth quarter. The Fed funds rate is currently hovering around 0.13%.
"Economic projections prepared by Federal Reserve Board staff as background for the June 16-17, 2015, meeting of the Federal Open Market Committee (FOMC) were inadvertently included in a computer file posted to the Board's public website on June 29," the Fed said in a statement.
An updated package of computer code of the board staff's model of the US economy posted online on 29 June inadvertently included three files containing staff economic forecasts that were confidential FOMC information, the central bank said.
Two files contained charts of the staff's projections for economic variables such as the unemployment rate, the core inflation rate and gross domestic product growth as well as the staff's assumption for the path of the federal funds rate target selected by the FOMC. Another file contained computer code used to generate a table displaying staff economic projections.
"The projections that were inadvertently released are staff projections that do not incorporate policymakers' views, including their views on monetary policy," the bank cautioned.
It added that the data leak was referred to the board's inspector general.
The Fed separately released board staff projections prepared for the June meeting of the FOMC, and noted that some of the data is different from that included in the leaked document. The new table showed slightly lower outlook for gross domestic product and inflation in 2015, as well as other revisions.
The Fed has policy meetings scheduled for 28-29 July, 16-17September and 27-28 October. The leaked data suggests that the central bank would decide to increase rates in any of these meetings before the 15-16 December meeting.
The development comes as a further blow to the Fed's reputation for secrecy around policy matters.
"It regrettably appears once again that proper internal controls are not in place to safeguard confidential Federal Reserve information," said Representative Jeb Hensarling of Texas, a Republican who chairs the House Financial Services Committee.
Officials at the Fed are already probing an alleged leak of market-sensitive information to a private financial newsletter in 2012.