Police have revealed that a sword seized in recent Sydney counter-terror raids was made of metal, not plastic as its owner claimed.

Australian Federal Police Commissioner Andrew Colvin emphatically rejected during a Senate estimates hearing on Thursday night claims the sword was plastic.

Australian Federal Police Commissioner Andrew Colvin. Credit:Rick Rycroft/AP

"Senator I'm pleased that you've asked this question," he told Liberal Democrat Senator David Leyonhjelm.

"I can absolutely guarantee the committee it was not a plastic sword. It was a metal sword," Mr Colvin said. "Categorically I can say that it was a metal sword."