The State Department is revising its annual report on terrorism amid concerns that it significantly undercounted the number of attacks last year.
Administration officials had hailed the reduced number of incidents as a sign the war on terrorism is working.
But the department says now revised figures could be "up sharply" from those first reported according to the Los Angeles Times, the new number could be a 20-year high.
The report, Patterns of Global Terrorism, said there were 190 international terrorist attacks in 2003, down from 198 in 2002 and 346 in 2001.
The 307 people killed in 2003 attacks was down from 725 the year before. Fewer people were wounded in attacks in 2003 than 2002, the report said.
Deputy Secretary of State Richard Armitage told reporters in April, "you will find in these pages clear evidence that we are prevailing in the fight."
"Last year, we saw unprecedented collaboration between the United States and foreign partners to defeat terrorism," State Department counterterrorism chief Ambassador Cofer Black said in April. "We also saw the lowest number of international terrorist attacks since 1969, and that's a 34-year low."
But now the Web version of the report contains the note: "The statistics that were used in compiling this report are currently being reviewed for accuracy. Any corrections will be posted here."
"Based on our review, we have determined that the data in the report is incomplete and in some cases incorrect," said a State Department statement released Thursday. "Here at the Department of State, we did not check and verify the data sufficiently."
The statement said the data in the report was gathered by the Terrorist Threat Integration Center, an office launched just last year combining staff from the CIA, FBI. Homeland Security and Pentagon. The TTIC is now conducting a review of its numbers.
"While we are still checking data for accuracy and completeness, we can say that our preliminary results indicate that the figures for the number of attacks and casualties will be up sharply from what was published," the statement read.
The department said revised figures would be issued as soon as possible.
The State Dept. said when it released the report in April that some attacks in Iraq would not be included because they were classified as military attacks on an armed force, not attacks against civilians.
But a review of the report indicates other possible omissions. For example, the report's "Chronology of Significant Terrorist Incidents" does not appear to mention any attacks in Russia or Chechnya, despite wire reports of at least eight attacks there that left at least 160 people dead.
The apparent omissions include the suicide bombing of a commuter train near Chechnya in December that killed 41 people and injured nearly 200, the August 1 bombing of a military hospital that killed 33, the twin suicide bombers who killed 14 people at a Moscow concert in July, and the more than 70 people slain in two attacks in May.
If changes are made, it would be the second time the report has been revised. Department officials denied any political considerations drove the way the numbers were counted. Some said any flaws in the report might be because responsibility for monitoring attacks recently was transferred from the CIA to the administration's Terrorist Threat Integration Center.
The 181-page report offered a country-by-country review of terrorist attacks and cooperation in fighting terrorism.
In it, Black said al Qaeda "is no longer the organization it once was. ... Most of the group's senior leadership is dead or in custody, its membership on the run and its capabilities sharply degraded." He said more 3,400 al Qaeda suspects have been detained worldwide.
The fight against terrorism "will be of uncertain duration, but additional deadly attacks are certain," Black warned.