Malcolm Turnbull has declared any new laws aimed at bolstering national security and prosecuting Australia's war on terrorism must not be allowed to erode the rule of law or contravene the separation of powers in the constitution, in comments that suggest simmering cabinet tensions.

"We've obviously got to make sure that we protect the national security of Australia, we make a strong stand against this global threat of terrorism, and we also have to do so within the rules ... which above all of course is the constitution [with] which we all have to comply," he told Sky News.

His remarks, which followed references to the limits of governmental reach under the constitutionally enshrined separation of powers, suggest both cabinet tension over a controversial area of policy and that senior ministers are at odds with the stated intentions of Prime Minister Tony Abbott.

The Communications Minister, who spoke up in cabinet against an earlier proposal to give the Immigration Minister the power to strip Australians of their citizenship when they engaged in terrorist activities - even if it would render them stateless, now appears to have toughened his stance, concerned that expanded ministerial power to cancel citizenship in the case of dual nationals without a court conviction is a step too far.