In an embarrassing admission, the State Department has acknowledged that the global terrorism report it issued in late April contained significant errors and that a corrected edition being prepared will show that terrorist attacks and fatalities in 2003 increased, rather than declined as initially stated.

The State Department began a review of the report earlier this month after private terrorism experts publicly challenged the figures contained in it, saying that some major incidents of international terrorism last year had been omitted.

When it launched the report April 29, State Department officials hailed the purported terrorism decline as "good news" and clear evidence that the United States was prevailing in the fight against terror.

After hearing the subsequent criticism of the document, a senior Democrat in the House of Representatives, Henry Waxman, wrote Secretary of State Colin Powell saying it was "deplorable" that the report had claimed a decline in attacks while in fact significant terrorist activity was, he said, at a 20-year-high.

In a talk with reporters Thursday, Mr. Powell acknowledged the reporting errors, calling them "very disturbing." But he insisted they were the result of poor coordination between the State Department and other agencies tabulating terrorist incidents and "had nothing to do" with any attempt to manipulate the figures.

Those comments were echoed by State Department spokesman Richard Boucher, who said the CIA, FBI and other agencies contributing data had differing definitions of terrorist acts and the time-frame covered by the report.

"When we got the data here at the State Department, I have to say we obviously did not check it thoroughly enough or verify the conclusion that had been reached because of the apparent change in the numbers and so we got the wrong data and we didn't check it enough," he said. "I think that's the simplest explanation for what happened. As the secretary said outside, there was no attempt at manipulation or political distortion. But we did walk down a road that was the wrong one."

Mr. Boucher said he could not be precise about the figures that will be in the corrected report, expected within a few weeks, but he said numbers would be sharply higher than the 190 acts of terrorism and 307 deaths attributed to them that were cited in the original document.

He also said he expected that terrorism overall will be shown to have increased in 2003 from the previous year, rather than the decline depicted in the original document.