China and the Cook Islands on Friday signed a comprehensive strategic partnership agreement, but the lack of transparency around the details has alarmed New Zealand, the South Pacific state’s closest democratic ally.

The decision drew from New Zealand, which is increasingly cautious about China's growing presence in the Pacific region.

In 2018, in a meeting with leaders from eight Pacific island countries, including then Cook Islands Prime Minister Henry Puna, Chinese President Xi Jinping agreed to elevate China's diplomatic ties with the group of nations.

The Cook Islands needs trade and investment. Its economy depends on tourism, and, having graduated to “high-income” status in 2020, it is no longer eligible for aid. As Mr Brown sees it, China is part of the solution.

The Cook Islands said on Saturday that it signed a comprehensive strategic partnership deal with China - a move expected to raise concerns in New Zealand with which it has constitutional ties. The deal was signed by Cook Islands Prime Minister Mark Brown during a visit to Beijing.

No details have been released, but analysts and environmentalists fear it will pave the way for closer security ties and the start of deep-sea mining.