Nauru is refusing to let an ABC camera operator cover Malcolm Turnbull's visit to the tiny island nation because the ABC is an "activist media organisation".
The rejection has drawn condemnation from Labor leader Bill Shorten, the Australian and New Zealand press galleries and the Vanuatu Daily Post but Malcolm Turnbull is refusing to intervene.
"It is up to Nauru. We respect their sovereignty but obviously we prefer to have events like this open to all the media," the prime minister told reporters in Sydney on Monday.
The tiny island nation based the decision on what it called the ABC's "blatant interference" in domestic politics before the country's 2016 election and a lack of respect toward President Baron Waqa.
"The Australian media do not decide who enters Nauru," it said in a statement on Tuesday.
The ABC camera operator was to be part of a three-person Australian media pool at the forum in September, alongside a journalist and photographer from AAP.
The situation is at an impasse with ABC News Director Gaven Morris saying Nauru shouldn't be allowed to dictate who fills the Australian media pool for an international event.
"The ABC does not intend to vacate our position in the media pool covering the Pacific Islands Forum in Nauru," he said in a statement.
"It can hardly claim it is 'welcoming the media' if it dictates who that media will be and bans Australia's public broadcaster."
But Nauru said the ABC's insistence on being part of the pool was "arrogant, disrespectful and a further example of the sense of entitlement shown by this activist media organisation".
The central Pacific nation has a population of about 11,000 people and will host the annual Pacific Islands Forum between September 1 and 9 for delegates from more than 30 countries, including 18 member states.
Mr Shorten said the government should stand up for the ABC, while Federal Press Gallery president David Crowe said the ban was an outrageous restriction on press freedom.
The Department of Foreign Affairs and Trade called Nauru's decision "regrettable" and Amnesty International said it was an attempt to suppress coverage of the treatment of asylum seekers in the Australian-funded offshore processing centre.
"Nauru's decision to ban media based on unfavourable coverage is a clear violation of freedom of expression, as is necessary in a healthy democracy," NZ press gallery chair Stacey Kirk said.
The Vanuatu Daily Post said it wouldn't cover the event unless everyone was allowed in.
Australia's role in the Pacific has been under intense scrutiny, as China increases its presence in the region.