Washington, July 6: In the six-and-a-half years that the US government has been fingerprinting insurgents, detainees and ordinary people in Afghanistan, Iraq and the Horn of Africa, hundreds have turned out to share an unexpected background, FBI and military officials said. They have criminal arrest records in the United States.

There was the suspected militant fleeing Somalia who had been arrested on a drug charge in New Jersey. And the man stopped at a checkpoint in Tikrit who claimed to be a dirt farmer but had 11 felony charges in the United States, including assault with a deadly weapon.

The records suggest that potential enemies abroad know a great deal about the United States because many of them have lived here, officials said. The matches also reflect the power of sharing data across agencies and even countries, data that links an identity to a distinguishing human characteristic such as a fingerprint.

“I found the number stunning,” said Frances Fragos Townsend, a security consultant and former assistant to the president for homeland security. “It suggested to me that this was going to give us far greater insight into the relationships between individuals fighting against US forces in the theater and potential US cells or support networks here in the United States.”

The fingerprinting of detainees overseas began as ad-hoc FBI and US military efforts shortly after the September 11, 2001, terrorist attacks. It has since grown into a government-wide push to build the world’s largest database of known or suspected terrorist fingerprints. The effort is being boosted by a presidential directive signed June 5, which gave the US attorney general and other cabinet officials 90 days to come up with a plan to expand the use of biometrics by, among other things, recommending categories of people to be screened beyond “known or suspected” terrorists.

Fingerprints are being beamed in via satellite from places as far-flung as the jungles of Zamboanga in the southern Philippines; Bogota, Colombia; Iraq; and Afghanistan. Other allies, such as Sweden, have contributed prints. The database can be queried by US government agencies and by other countries through Interpol, the international police agency.

Civil libertarians have raised concerns about whether people on the watch lists have been appropriately determined to be terrorists, a process that senior government officials acknowledge is an art, not a science.

Large-scale identity systems “can raise serious privacy concerns, if not singly, then jointly and severally,” said a 2007 study by the Defense Science Board Task Force on Defense Biometrics. The ability “to cross reference and draw new, previously unimagined, inferences,” is a boon for the government and the bane of privacy advocates, it said.

The effort, officials say, is bearing fruit.

“The bottom line is we’re locking people up,” said Thomas E Bush III, FBI assistant director of the Criminal Justice Information Services division. “Stopping people coming into this country. Identifying IED-makers in a way never done before. That’s the beauty of this whole data-sharing effort. We’re pushing our borders back.”