MANILA — President Obama called on China on Wednesday to halt its construction on reclaimed islands in the South China Sea, raising the contentious issue at the start of a two-day economic summit meeting at which he and other Pacific Rim leaders also discussed trade and climate change.
Speaking to reporters after a meeting with President Benigno S. Aquino IIIof the Philippines, Mr. Obama directly confronted the disputed Chinese claims over islands in the critical waterway. He urged the Chinese to stop military activities there and endorsed a process of arbitration to settle differences between Beijing and its Southeast Asian neighbors.
“We agree on the need for bold steps to lower tensions, including pledging to halt further reclamation, new construction and militarization of disputed areas in the South China Sea,” Mr. Obama said.
The president’s comments on Wednesday came at the start of the Asia-Pacific Economic Cooperation summit meeting, at which leaders from 19 regional economies have gathered for a series of discussions about growth and trade.
The centerpiece of those discussions on Wednesday was the Trans-Pacific Partnership Agreement, which was reached recently by a dozen countries, including the United States. Mr. Obama hailed the deal at a meeting with other leaders.
“This is the highest standard and most progressive trade deal ever concluded,” he said, standing beside Michael Froman, the United States trade representative, who helped negotiate the pact. “It includes strong protections for workers, prohibitions against child labor and forced labor. It has provisions to protect the environment, to help stop wildlife trafficking, to protect our oceans.”
The agreement still faces an intense debate in the United States as Congress considers it. But Mr. Obama expressed confidence that it would be approved.
“The fact that everyone here has stepped up and made some hard decisions that are going to pay off for decades to come I think is testimony to the vision that was reflected,” he said.
Mr. Obama also used the summit meeting to push for his climate change agenda, telling a group of chief executives that the world must face what he called an “urgent and growing threat of climate change” before time runs out.
He said the economic and social threats from climate change should be of particular concern to the people of Southeast Asia, where many low-lying islands could face disaster as sea levels rise.
“Few regions have more at stake in meeting this challenge than the Asia-Pacific region,” he said.
Mr. Obama is scheduled to travel to Paris at the end of the month to kick off a climate change summit meeting that aims to reach an accord dedicating many nations to reducing their carbon emissions in the interest of slowing global warming.
The president used the topic of climate change on Wednesday to host a discussion at a chief executives’ forum along with Jack Ma, founder of the e-commerce giant Alibaba, and Aisa Mijeno, an entrepreneur from the Philippines who invented a lamp that runs on saltwater.
In response to a question about her lamp from Mr. Obama, Ms. Mijeno said that it provided about eight hours of light, as well as power to a USB port for charging a phone.
“And all you need to do is you just have to replenish the saltwater solution,” she said, “and then you have another eight hours of lighting.”
Mr. Ma offered the president the perspective of a very large company that, he said, spends 0.3 percent of its revenue to encourage young people to find creative ways to help the environment. He said that when he was 12, he almost drowned in a lake, and now that lake is dry.
“If we do not care about this earth, we do not care about the water, food, environment, I think nobody can survive, whether you’re big or small,” Mr. Ma said. “So this is the concern. This is the worry I have.”
Mr. Obama was scheduled to end the day with a working dinner to further discuss economic issues.