Image copyright AP Image caption Both the Australian (R) and New Zealand (L) flags feature the Union Jack

Australia's foreign minister says there is "no great demand" to change the national flag, a day after New Zealand announced a referendum on the subject.

Julie Bishop, who is visiting the UK, said she believed Australia would "stick with" the current flag.

Both the Australian and New Zealand flags include the Union Jack - the UK's national flag.

New Zealand's PM said on Tuesday that the flag represented history from which New Zealand had moved on.

Speaking late on Tuesday, Ms Bishop said changing the flag was "not an issue that actually draws much attention in Australia".

"There's no great demand to change it and many Australians have fought and died under that flag, sadly," she said.

"We have competed in Olympic Games under that flag and there's a sense of pride in it."

Opposition leader Bill Shorten also said he was "not keen" to change the flag, saying it reflected Australia's history.

The referendum in New Zealand is to be held within the next three years, Prime Minister John Key announced on Tuesday.

"It's my belief... that the design of the New Zealand flag symbolises a colonial and post-colonial era whose time has passed," he said in a speech.

Mr Key said that he liked the silver fern - popularised by national teams including the All Blacks - as an option.

But he said he was open to all ideas and that retaining the current flag was "a very possible outcome of this process".

A group of cross-party lawmakers would oversee the vote process and a steering group would seek public submissions for new flag designs, he said.