A postal ballot has opened in New Zealand to allow the public to choose one of five shortlisted designs for a new national flag - though it won't be until next year that Kiwis decide whether they want to get rid of the current one.

New Zealanders have just under a month to choose between five bold new flags, reports the BBC. Two are in black and white and three feature a fern design based on the local plant that has given many New Zealand sporting teams their nicknames and which was often used by the indigenous Maori people as bedding.

Whichever flag wins, there is no guarantee it will ever be used: in 2016 there will be a national referendum on whether to scrap the existing standard, which features the British Union Flag in one corner and the stars of the southern cross on a blue background.

New Zealand's prime minister, John Key, favours ditching the current flag as he believes it is not representative of the country and is too similar to the Australian flag. According to the Daily Telegraph, he wants a standard which "screams 'New Zealand!'"

However, polling suggests most New Zealanders would prefer to stick with what they've got, reports the BBC - and Key has apparently admitted this is the case.

The flags have been chosen from designs submitted to an open competition. Some of the wackier options have been weeded out - including one which featured a kiwi bird shooting lazer beams from its eyes.

The entrants were whittled down to four but a fifth was allowed in after complaints that the options were all too similar. One striking black and white design features a traditional spiral Maori symbol, the koru.

Communities with enough flag poles have been given real versions of the flags to fly so the public can see them in action before making a choice.