The Pacific Islands Forum has ended its annual meeting, with leaders agreeing to cooperate more closely on climate change and security issues.

The 18-member forum, including Pacific island nations and Australia, held a closed-door summit on Thursday to wrap up the four-day meeting in Suva, the capital of Fiji.

Fijian Prime Minister Josaia Voreqe Bainimarama, who chaired the summit, told reporters that the region is facing complex challenges, and unity is the overriding focus. He said there is no doubt about the importance of working together on climate change and other shared challenges.

The closed-door leaders' meeting also reportedly discussed security issues, with China's growing influence in the region in mind.

According to the forum's secretariat, the leaders confirmed that they will share information before going ahead with security pact talks with other countries.

This year's summit took place following the announcement from Kiribati that it would leave the forum, over differences with some other members last year regarding the election of a new secretary general.

The leaders of six other countries and regions were absent, citing reasons such as local elections.

Concern is being raised that the disarray among the members of the Pacific Islands Forum could allow China to further strengthen its presence in the region.