Australia's push for a fresh agreement to drop trade barriers with Pacific island nations has suffered a setback after the Solomon Islands backed an attempt by Fiji to scuttle negotiations.

As the Pacific Islands Leaders Forum is set to start in Cairns tomorrow, it has been revealed that Solomon Islands Foreign Minister William Haomae has written to governments across the Pacific supporting Fiji’s complaints that any talk of a new trade deal is in breach of the existing arrangements.

In his letter obtained by The Age, Haomae registers the Solomon Islands support for Fiji and said that there be no further discussion of PACER matters until further consultations.

It follows a declaration by Pacific countries, including Papua New Guinea, Fiji and Vanuatu last month that said the exclusion of Fiji would render agreements null and void.

And attempts by Australia and New Zealand to put the Fiji issue aside for now may be frustrated after the summit last month of the Melanesian Spearhead Group.

In a communique at the end of the MSG Summit, PNG, Solomon Islands and Vanuatu called on the Pacific Forum to maintain an open and constructive dialogue with Fiji.

Fiji will be absent from the forum in Australia starting tomorrow, due to the suspension from the forum.

Prime Minister Commodore Voreqe Bainimarama had earlier said that he was ready to engage with the forum if the suspension is lifted.

But he said he has confidence in the MSG leaders who will represent him in the discussions.