The Chinese warships off Australia's coast are carrying missiles with a range of about 1,000 kilometres, New Zealand's defence minister says, warning of an urgent need for her government to bolster defence spending.

When geopolitical tension mounts, New Zealand tends to lean closer to traditional allies. Chinese warships in the Tasman make that even likelier now.

Australia warned airlines flying between Australian airports and New Zealand to beware of Chinese warships potentially conducting a live-fire exercise in the Tasman Sea

The defence ministry has hit back at Australia’s response to its naval exercises off the east coast, labelling Canberra’s protests as “unreasonable”.

The verbal crossfire follows Australia’s complaint that it did not receive sufficient notice of a military drill conducted by Chinese warships on Friday.