World leaders have been reacting to US President-elect Donald Trump's statement earlier this week that he intends to pull out of a major cross-Pacific trade agreement on his first day in office.

A dozen countries have signed on to the Trans-Pacific Partnership, or TPP, agreement, including the US. Together, the members account for around 40 percent of the world's economy.

So far, the TPP has only been signed. It hasn't yet been ratified by all of those 12 countries. And the chance of the happening are looking slimmer.

US President-elect Donald Trump confirmed his intentions to skip out of the agreement in a video message recorded earlier this week. It was part of a broader statement meant to reveal what Trump intended to do during his first 100 days as President when he takes the oath of office in January.

Reaction was swift. US President Barack Obama, attending a leaders meeting in Peru, said not moving forward on the TPP would undermine the US.

"I believe that TPP is a plus for America's economy, America's workers, American jobs. I think not moving forward would undermine our position across the region, our ability to shake the rules of global trade in a way that reflects our interests and our values," he said.

Meanwhile, Japanese Prime Minister Shinzo Abe - who has been a leading advocate of the deal, and was the first foreign leader to meet with Trump since the elections  - said the TPP would be quote "meaningless" without Washington's involvement.

Australian Prime Minister Malcolm Turnbull said he would respect any US decision, but noted he hoped that Donald Trump - once he's actually IN office - might have a change of heart.

China, of course, is not a signatory to the agreement, and has been pushing an alternative plan called the Regional Comprehensive Economic Partnership. The RCEP focuses exclusively on Asia; it does not currently include countries in the Americas.

Speaking in South America this week, the Chinese President Xi Jinping called for greater cross Pacific trade. Chinese officials didn't specifically respond to Trump's comments, but said Beijing would be open in principle to all trade arrangements that comply with global trade rules.