Flag reflects Aust identity: Shorten

Labor leader Bill Shorten has given bipartisan support to the Australian flag, after a push to change New Zealand's raised questions about Australia's plans to ditch the Union Jack.

New Zealand's Prime Minister John Key wants to change its flag to a black one with a silver fern, prompting questions of Australian Foreign Minister Julie Bishop during a visit to Britain.

"I believe we will stick with the flag. There's no great demand to change it," she said.

Mr Shorten said the Australian flag reflected Australia's history and diversity.

"I think our flag describes our history, describes the unique Australian identity we have," he told reporters in Perth.

However, the opposition leader supported a debate on Australia becoming a republic.

"I think it is long overdue to have an Australian head of state," he said.

Ms Bishop said Australia would keep the its flag and Queen "for the time being most certainly".