U.S. government statistics show a dramatic spike in the number of significant international terrorist attacks last year - figures the State Department has decided not to make public.

Aides working for opposition Democratic lawmakers say the State Department revealed the data in a private briefing to Congress. The aides say the statistics show an all-time high of about 650 terrorist attacks in 2004, compared to 175 the year before.

They say the number of attacks in Iraq numbered 198 - up from 22 in 2003.

Last week, the State Department said it would break with tradition and not include the figures in its annual report on global terrorism.

In last year's report, the data was found to be drastically understated, prompting the State Department to issue a revision. Some members of Congress say this year's figures are not being disclosed because they might undermine the Bush administration's claim that U.S.-led allies are winning the global war on terror.