China will be able to establish a "significant strategic presence" in the Pacific following its new agreement with the Cook Islands, a security studies professor says.
The Cook Islands has signed a memorandum of understanding with China, including a five-year agreement for seabed mineral exploration and research.
The two countries have also agreed to promote investment and cooperation in the 'blue economy', relating to marine activities generating economic value.
Massey University associate professor Anna Powles said that included China building ships, ports and wharves in the islands.
"These can be considered to be critical infrastructure, or strategic infrastructure, and there are national security implications for New Zealand, and for the Cook Islands, as a consequence of this development.
"China, through commercial actors, will be able to establish a significant strategic presence and reach into the Pacific."
The infrastructure would support the dozens of extra Chinese coastguard vessels registered in the Pacific last year, Powles said.
"A number of those vessels are very large, very sophisticated, one of them which is larger than any Australian naval fleet.
"So we may very likely see increased presence in our immediate region of Chinese coastguard vessels."
News of the deal landed soon after China began conducting live firing exercises from naval vessels in the Tasman Sea.
The part of the agreement relating to mineral exploration was likely to increase friction between Pacific nations, Powles said - because New Zealand and a number of other Pacific countries had signed up to a ban on deep sea mining.
The Cook Islands government said the memorandum of understanding did not involve any agreement to give an exploration or mining licence.
Powles said the Cook Islands government had long believed it would benefit from deep sea mining, linking it to greater economic independence - and potentially independence from New Zealand.
A spokesperson for Foreign Minister Winston Peters said the government would be looking over the agreements signed between the Cook Islands and China.
"We will now analyse the contents of these agreements - focusing on the implications they have for New Zealand, the Cook Islands people and the Realm of New Zealand."
New Zealand had already accused the Cook Islands government of a lack of consultation and transparency over the wider partnership agreement with China.
