Australia's prime minister has used his official campaign launch to warn against a change of government during the ongoing economic fallout from Britain's decision to leave the European Union.

Polls are projecting a win for Prime Minister Malcolm Turnbull's conservative coalition next Saturday for a second three-year term with a reduced majority.

Turnbull said on Sunday at the Sydney launch his government was better placed to strike vital new trade deals with the EU and Britain after the separation forced by a British referendum.

He says Australia has struck free trade deals with major trade partners China, Japan and South Korea and renegotiated a pact with Singapore during the government's first term.

Opposition leader Bill Shorten says the government is divided.