Prime Minister Jacinda Ardern is under fire for taking longer than she had indicated to make moves on the two-way travel bubble with the Cook Islands.

Speaking to media with Cook Islands Prime Minister Mark Brown on Friday, Ardern revealed the two Governments were working towards a bubble start date in May.

This is despite saying in December that the Government was aiming for the bubble to be opened before April.

The Cook Islands – which relies heavily on tourism – has seen its GDP contract by 20 per cent because of the drop-off in international travel.

Brown was upbeat about the prospects of the bubble.

"We have asked for a date for the commencement of [the bubble] … and I'm happy that the month of May is where we're indicating that travel will begin between our two countries."

The delay in announcing a Cook Islands bubble comes after the Government also failed to announce the start date of a trans-Tasman travel bubble – with Ardern instead announcing on Monday that an announcement will be made on April 6.

At a post-Cabinet press conference, she acknowledged New Zealanders want certainty about the bubble, but it is "highly complex".

It needs all technical issues resolved and appropriate regulatory mechanisms in place, Ardern said.

She said there have been 12 meetings between Australian and New Zealand officials about the travel bubble. The Government was looking at a state-by-state bubble.

"We are having to create a brand new rulebook."

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