WASHINGTON — The federal government reports that the number of documents being classified jumped 10% last year to 15.6 million, driven largely by military operations in Iraq and Afghanistan.

The numbers come from the Information Security Oversight Office in its latest annual report to the president.

The number of pages that the government declassified continued to drop. Last year, 28.4 million pages were declassified, a 34% drop from the previous year.

The increase in the number of documents being classified has raised concerns that the government is being too secretive, and the report notes that overclassification of documents has been a consistent issue for decades. However, the report stops short of saying that the trend runs counter to the nation's interest.

"It cannot be said conclusively from this report's data that recent increases in the number of classification decisions were due substantially to the phenomenon of overclassification," the report states.

The report, dated March 31, notes that classifying information is an essential and proven tool for defending the nation, but says that it can be a double-edged sword. For example, it said limits on information can contribute to friendly-fire deaths on the battle field, and failure to share information contributed to the government's failure to intercept the plot that led to the Sept. 11 terrorist attacks.

"Simply put, secrecy comes at a price. For classification to work, agency officials must become more successful in factoring this reality into the overall risk equation when making classification decisions," the report said.