Officials caution that much of the increase, due to be reported publicly next week, stems from a change last year in how terror attacks are counted, coupled with a more aggressive effort to tally such violence worldwide.

But the documents say, and officials confirm, that some of the rise is traceable to the war in Iraq, where foreign terrorists, a homegrown insurgency and sectarian strife have all contributed to political bloodshed.

More than half the fatalities from terrorism worldwide last year occurred in Iraq, said a counterterrorism official, who spoke on condition of anonymity because the data haven't been made public. Roughly 85 percent of the U.S. citizens who died from terrorism during the year died in Iraq.

The figures cover only noncombatants and thus don't include combat deaths of U.S., Iraqi and other coalition soldiers.

''There's no question that the level of terrorist attacks in Iraq was up substantially,'' said the official, who's familiar with the methods used by the National Counterterrorism Center to track terrorist trends. The center is part of the U.S. intelligence community.

There were 3,192 terrorist attacks in 2004, the center reported last July.

Last year, while compiling the 2004 numbers, analysts switched to a dramatically broadened definition of what constitutes terrorism. The same definition was in use for the 2005 data, but analysts had more time to use the new method.

In the past, intelligence analysts had counted only ''international terrorism,'' defined as attacks involving citizens or territory of more than one country. But officials concluded that the definition was outdated and undercounted terrorism. The 2004 sinking of a ferry in the Philippines by Filipino guerrillas that left 132 people dead was omitted, for example.

The latest figures will be released in conjunction with the State Department's annual report on terrorism, which covers broader trends.