The Secretary-General of the Pacific Islands Forum says the organisation remains the premier grouping for regional political decision-making.
Tuiloma Neroni Slade says he doesn't view the new Pacific Islands Development Forum as a threat to the Pacific Islands Forum's primacy.
Fiji's government said the PIDF was established because there was no regional body where government, the private sector and NGOs can discuss sustainable development.
But Mr Slade says the Forum has a proven record of integrity, widespread support in the region as well as substantial global support.
And he says it is already focussed on inclusive sustainable development.
"It includes all stakeholders: governments, private sectors, civil society in all its levels and therefore you need to ask yourself: what is the justification for yet another Forum?"
Tuiloma Neroni Slade