'Possible criminal offence' in union raids, AFP say

The Australian Federal Police believes a criminal offence may have been committed in relation to leaks about raids on union premises linked to Jobs Minister Michaelia Cash's office.

The AFP has referred evidence to the commonwealth prosecutor after investigating raids on Australian Workers' Union headquarters in Sydney and Melbourne last October.

"We do believe an offence may have been committed," AFP deputy commissioner Leanne Close told a Senate hearing on Friday.

The AFP is investigating the leak of information which led to media being tipped off and arriving before police raiding the offices.

Ms Close said dozens of people had been interviewed during the investigation, but refused to say if government ministers including Senator Cash had assisted police.

AFP officers raided the union offices last year as part of an investigation by the Registered Organisations Commission.

One of Senator Cash's media advisers quit after admitting to telling media about the raids.

Under questioning from Labor senator Murray Watt, Ms Close said it could jeopardise the investigation if she confirmed or denied if ministers had been interviewed.

Liberal senator and committee chair Ian Macdonald said the AFP's refusal to rule out investigating Senator Cash proved nothing.

- AAP