China, the United States and Taiwan have all been barred from the annual Pacific Islands Forum in Honiara next month, an event they usually attend.

China counts the Solomon Islands among its closest partners in the South Pacific and signed a secretive security pact with Honiara in 2022.

It has been accused of agitating behind the scenes to see Taiwan excluded from attending the Forum as an observer.

The Pacific bloc's top diplomats met in Fiji on Thursday to discuss the Forum's agenda, and Solomon Islands Foreign Minister Peter Shanel Agovaka said his nation was not influenced by China.

"Our focus is not on China or Taiwan. Our focus is on the (Pacific) region," Agovaka told AFP.

He expressed frustration and blamed the Forum secretariat for the ban because it was yet to agree on "dialogue partners".

Agovaka added that the Forum was "all over the place".

New Zealand Foreign Minister Winston Peters had earlier warned that "outsiders" interfering with Forum decisions threatened to split the bloc.

Peters did not mention China by name, but said the issue would be raised during the foreign ministers' meeting.

"We've got to make sure that every outsider comes here with respect for those of us who are inside the organisation," he said.

Agovaka defended the presence of such observers at Forum meetings.

"They enhance our meetings," he said.

- 'Very perplexing' -

Communist China has never ruled Taiwan, but Beijing insists the island is part of its territory and has threatened to use force to bring it under its control.

China and Taiwan have long vied for diplomatic influence in the South Pacific and elsewhere, with Beijing spending hundreds of millions of dollars building sports stadiums, presidential palaces, hospitals and roads in Pacific island nations.

Peters later described Agovaka's comments as "very perplexing".

"At this point in time, when aid from another source or other countries is desperately needed and we're out there trying to get it, if the message is we're not interested in seeing you, how's this going to fall?" he said.

Chinese officials described accusations they were agitating behind the scenes as "misinformation".

"China has participated in every Forum dialogue, and remains committed and looks forward to continuing such engagement," a spokesperson for the Chinese Embassy in the New Zealand capital said.

The annual pre-Forum meeting of foreign ministers is typically a light-hearted affair, although the gathering in Suva on Thursday was noticeably more tense.

Several countries did send ministers and others did not engage fully.

Nauru's representative left, smoking a cigar, after only one morning session.

"We're going to sort things out... we'll get things back on an even keel," Peters said.

The Forum will be held in Honiara from September 8-12.