WASHINGTON (Reuters) - The U.S. government has been using its border checkpoints to collect information on citizens that will be stored for 15 years, raising concern among privacy advocates, the Washington Post reported on Wednesday.

Department of Homeland Security (DHS) officials said the collection is part of a broader effort to guard against terrorist threats, the report said, citing a Federal Register notice the agency issued last month.

Officials said the disclosure is among a series of notices to make the department's data gathering more transparent, the newspaper reported.

A notice by Customs and Border Protection, a DHS agency, said it does not perform data mining on border crossings to search for patterns that could signal a terrorist or law enforcement threat, according to the Post.

But it states that information may be shared with federal, state and local governments to test "new technology and systems designed to enhance border security or identify other violations of law," the Post reported.

A DHS spokesman was not immediately available for comment on the report.

Information on international air passengers has long been collected this way but Customs and Border Protection only this year began to log the arrivals of all U.S. citizens across land borders, the Post said.

Privacy advocates raised concerns about the expanded collection of personal data and said safeguards are needed to ensure the system is not abused.