The Chinese naval presence currently in the Tasman Sea is 'extremely capable', with one of the warships carrying ballistic missiles with a range of 1,000km, New Zealand's Defence Minister has warned. 

New Zealand confirmed the second day of exercises in the Tasman Sea on Saturday after a Chinese warship was seen firing a gun.

It came after three vessels of the People's Liberation Army Navy conducted drills about 630km off Eden, NSW in recent days. 

Qantas, Emirates, Virgin and Air New Zealand modified flight paths between Australia and New Zealand after receiving initial reports of live firing on Friday. 

China's defence Ministry spokesman Wu Qian hit back on Sunday to accuse Australia of deliberately 'hyping up' the danger, claiming they had acted in 'full compliance with international law'.

'Australia, knowing this well, made unreasonable accusations against China and deliberately hyped it up,' Mr Qian said. 

'We are deeply surprised and strongly dissatisfied with this.'

But on Monday New Zealand's Defence Minister Judith Collins said the claim that they acted in accordance with international practices was 'wrong'. 

Ms Collins said that China should have given up to 48 hours notice before the flotilla of naval ships started firing and described the exercises as 'unusual'.

'There was a warning to civil aviation flights that was basically a very short amount of notice - a couple of hours - as opposed to what we would consider best practice, which is 12 to 24 hours' notice so that aircraft are not having to be quickly diverted when they're on the wing,' Ms Collins told RNZ. 

She added: 'The weapons they have are extremely capable. One has 112 vertical launch cells and has reported anti-ship ballistic missile range of 540 nautical miles.'

Ms Collins said they were closely tracking the ships after China had so far ignored requests from New Zealand for more information.

'We're taking them at face value that they are undertaking normal transits when it comes to the UN Convention on the Law of the Sea, that they're not breaking the law. 

'But as we've said, it is always better to give a lot more notice when it comes to live firing.'

Ms Collins said the ships were currently around 280 nautical miles east of Tasmania. 

On Sunday, Health Minister Mark Butler said China had 'the right' to conduct drills as the warships were in international waters.

Both Prime Minister Anthony Albanese and Defence Minister Richard Marles have also both said the Chinese warships' activities were legal under international law. 

However defence opposition spokesman Andrew Hastie has slammed the pair over their handling of the situation.

'When will the Prime Minister and his Defence Minister stand up for the Australian national interest and insist on mutual respect from their Chinese counterparts,' Mr Hastie said. 

He said China's growing military presence was 'gunboat diplomacy', and that the Communist state was trying to project power into the Pacific region and test US allies such as Australia. 

Mr Hastie pointed out there had been other incidents between Australian and Chinese forces in recent years, including dangerous manoeuvres by the People's Liberation Army.

'This is a weak government that is keeping Australians in the dark and failing at the most crucial role of government – to uphold our security and sovereignty,' he continued.

Mr Butler rejected those claims as he slammed the Opposition's ' juvenile' response.

'The Opposition (is) using a bit of loud hailer diplomacy again here for domestic political purposes,' he told Sky News.

'What do they say we should do? This is juvenile. This is student politics. They have not said one thing they would have the ADF do that we're not currently doing.

'It's all about the politics, including, bizarrely, in relation to national security.'

Foreign Minister Penny Wong met with her Chinese counterpart, demanding answers as to why the vessels only offered limited notice before the firing was carried out, on the sidelines of a G20 meeting in Johannesburg on Friday.