Former prime minister Tony Abbott has revealed he was advised against establishing the new counter-terrorism department unveiled by Malcolm Turnbull.
The prime minister on Tuesday described the move as the biggest change in national security for four decades.
Under the plan, which would come into force next year, a home affairs portfolio headed by Immigration Minister Peter Dutton would cover agencies including the Australian Federal Police, ASIO, Australian Border Force as well as customs and citizenship.
Mr Abbott has told 2GB radio the issue was raised when he was prime minister, but he was advised against it.
Speaking on Melbourne radio station 3-A-W, Mr Turnbull says he made a captain's call when he announced the security overhaul.
The Federal Opposition is unconvinced over the announcement of a new national-security ministry.
Opppsition Leader Bill Shorten says it is a case of politicising, with little evidence it is actually about national security.
