New Zealand is considering more quarantine-free travel opportunities for people vaccinated against Covid-19 after the country reopened its borders to Australia and will soon to the Cook Islands, Prime Minister Jacinda Ardern said on Thursday.

"Our goal now is to move towards reconnecting our people to the world," she said in her pre-Budget speech.

Since the trans-Tasman quarantine-free travel started April 19, more than 70,000 people have flied to New Zealand from Australia, and over 57,000 have travelled the other way, Xinhua news agency reported.

Quarantine-free travel will start between the Cook Islands and New Zealand from May 24.

Ardern said Niue is the next addition to the list, stressing that opportunities will be explored on quarantine-free travel with other countries although the task is "not without risk and complication".

The Prime Minister did not give any specific plans but promised that New Zealand will "keep an open mind".

Ardern will lead a trade delegation to Australia in July, which will be her first overseas travel since the pandemic started last year.

In June, Trade Minister Damien O'Connor will travel to London and Brussels to discuss free trade agreements with the UK and the European Union.