US immigration officials has launched an online tool to help people find illegal aliens who have been placed in US custody.

The Online Detainee Locator System (ODLS) is designed "to assist family members, attorneys and other interested parties in locating detained aliens" being held by Immigration and Customs Enforcement (ICE).

The search service is available at the ice.gov website.

"The ODLS is an easy, accessible tool that allows family members and counsel to locate an individual in ICE custody in a matter of minutes," said Phyllis Coven, acting director of ICE's office of detention policy and planning.

People can search by alien registration number or by name, birthday, and country of birth to learn where a person is being held, and telephone numbers to the facility as well as the ICE office in the region.

ICE said that the tool is part of a promised effort to modernise and improve operations at the agency, including reform of its detention systems.