Image copyright Getty Images Image caption The design titled Silver Fern (Black, White and Blue) came out tops

New Zealanders have picked a blue and black design with the silver fern as the preliminary winner in a referendum on a possible new national flag.

The runner-up is a similar-looking red, white and blue design.

The final result will be announced on Tuesday after late and overseas votes are counted, and may change as the winning margin is narrow.

A second referendum will be held in March to decide whether to adopt the new flag, or keep the existing one.

In pictures: Weird and wonderful entries that lost out

What do schoolchildren think of the new designs?

Image copyright Getty Images Image caption Silver Fern (Red, White and Blue) came in second

New Zealanders were asked to choose which of five designs they preferred.

About 48% of eligible voters took part in the first referendum, which has divided opinion in New Zealand over its cost and timing.

The preliminary winner and runner-up flags were both designed by architect Kyle Lockwood, and feature New Zealand icons the silver fern and the Southern Cross.

The second-runner-up was Red Peak, which was added to the ballot after a social media lobbying campaign.

Image copyright Getty Images Image caption Red Peak, by designer Aaron Dustin, was popular on social media but in the end came in third

Voting officially closed at 19:00 local time on Friday (06:00 GMT).

Media playback is unsupported on your device Media caption What do schoolchildren think of the new flag designs?

The decision to choose a new flag has been backed by Prime Minister John Key, who has said the current one is too similar to Australia's and that it is time to remove the Union Jack from the flag.

He said the turnout, which was higher than had been expected, showed "people are engaging" with the debate, the New Zealand Herald reports.

Media playback is unsupported on your device Media caption New Zealand long-listed 40 designs - but not any of these

Four designs were initially announced in September and Red Peak, was added weeks later.

Image copyright NZ Government Image caption The five flag finalists were criticised as being uninspiring

The entire exercise is expected to cost around NZ$27m (£12m, $18m).