The Cook Islands’ pact with China has been furiously denounced by New Zealand as breaching the neo-colonial constitutional arrangements with its Pacific neighbour.

New Zealand expressed renewed concern on Monday about the Cook Islands' prime minister travelling to China this week to sign agreements without properly consulting with Wellington despite the two nations' constitutional ties.

New Zealand has accused the Cook Islands government of a lack of transparency over its plans to strike a partnership deal with China. The tiny Pacific Island nation's leader, Mark Brown, is this week making his country's first ever state visit to Beijing in order to sign the agreement.