SYDNEY (Reuters) - Pacific island nations declared climate change to be their “single greatest threat”, urging Washington to return to the Paris Agreement on climate, just as Western powers seek to check China’s rising influence in the region.

FILE PHOTO: Attendees applaud at the conclusion of remarks at the opening ceremonies of the Paris Agreement on climate change held at the United Nations Headquarters in Manhattan, New York, U.S., April 22, 2016. REUTERS/Brendan McDermid

Australia, which has backed away from its own commitment to Paris without exiting the pact, was among the 18 nations of the Pacific Islands Forum that made the call at a meeting of leaders on the tiny island state of Nauru.

“Climate change presents the single greatest threat to the livelihood, security and well-being of Pacific people,” the leaders said in a communique, asking the United States to return to the climate pact.

Tuvalu Prime Minister Enele Sopoaga told a news conference: “The aspiration is for the U.S. to be in the Paris Agreement again because we cannot have comprehensive robust emission reduction unless the biggest emitter of greenhouse gas is there in the process, we cannot leave the U.S. out.”

However, participants said one country would not agree to even stronger language in the communique and Sopoaga made clear which it was, although he stopped short of naming it.

“The name of the qualifier (started with) alphabetical A, capital A,” Sopoaga told Wednesday’s news conference, held after the leaders’ meeting.

No forum member’s name, apart from Australia’s, begins with the letter ‘A’.

Australia’s representative at the meeting, Foreign Minister Marise Payne, declined to answer questions about Sopoaga’s comments.

“It is not appropriate to discuss the internal talks of the private Leaders’ Retreat,” Payne said in an emailed statement.

“Australia understands the importance that Pacific Countries place on effective global action to combat climate change,” she said.

The demand for action over the low-lying islands of the Pacific, seen as the front line of global climate change, comes as rising sea levels and other climate-related crises force residents to move to higher ground.

Against this backdrop, China’s vocal support for tackling global warming aids its drive to win allies and influence in the strategically significant and resource-rich area.

U.S. President Donald Trump, who has called climate change a hoax, pulled the United States out of the Paris Agreement in 2017, saying it favored other countries and put the United States at a disadvantage.

Climate change is domestic political dynamite in Australia, one of the world’s largest coal exporters which has also sought to push back against China’s influence in the Pacific.

Wednesday’s communique endorsed “with qualification” a separate, stronger statement from seven small Pacific Island states seeking “urgent resolution” of Paris rules to cap the rise in global temperatures at 1.5 degrees Celsius.

“If that cap is not reached, there are going to be serious problems on islands like Tuvalu,” Sopoaga said, citing an estimate of island submergence by 2030 from the U.S. Geological Survey.

“2030 is not far away, our grandchildren would still be growing up and the islands of Tuvalu and Kiribati and, maybe, part of Nauru would be submerged,” he said.