The Pacific Islands Forum has launched a "Blue Pacific Appeal" for Tonga.

Secretary-General Henry Puna said the initiative aims "to help mobilise financial support" to aid the Kingdom's recovery from the events of January 15.

"Our hearts go out to those in Tonga and the people of Tonga around the world who have been trying to find out more news of their loved ones and communities," he said.

"I send condolences to those grieving, the displaced communities, and the many who are rebuilding their lives and homes."

Puna said Forum nations have responded swiftly to assist Tonga "and provide confirmation of being ready to step in to assist, where required, when the time comes."

He said communications challenges in co-ordination of the response efforts by partners and organisations remain significant.

But the Forum continues to engage with the United Nations Office for the Coordination of Humanitarian Affairs (UNOCHA) to support the emergency response work.