Prime Minister Malcolm Turnbull is considering a proposal for a major restructuring of the federal government that would create a US-style Department of Homeland Security.

The stated aim of the plan is to improve co-ordination across the government in preventing terrorist attacks. It would merge at least half a dozen relevant federal agencies from two departments into a mega-department.

The enlarged department would be built on the existing Department of Immigration and Border Protection, which already includes the Australian Border Force.

The putative minister for homeland security would be the current Immigration Minister, Peter Dutton. Mr Dutton, the most senior conservative in the Turnbull cabinet, is understood to strongly favour the reorganisation.