A report from the United States department of justice has revealed terrorists on witness protection were allowed on board flights as their new identities were not added to the US no-fly list.

The Witness Security Program, organised by the department, had failed to give the new names to the FBI-managed Terrorist Screening Center, the report concluded.

This decision allowed had allowed a “small but significant number” of suspected or known terrorists to board airliners.

“It was possible for known or suspected terrorists to fly on commercial airplanes in or over the United States and evade one of the government’s primary means of identifying and tracking terrorists’ movements and actions,” explained the report.

The department of justice said procedures had now been updated.

Terrorism-linked witnesses have are eligible for federal protection, allowing them to be provided with new identities and resettled.