SEOUL, South Korea — China on Saturday lashed out at President Trump for accusing Beijing of not being supportive in efforts to denuclearize North Korea, while South Korea called the U.S. decision to call off a trip to the North by Secretary of State Mike Pompeo “unfortunate.”

The reaction in Seoul and Beijing came hours after Trump directed Pompeo to delay his trip because of what he saw as a lack of progress on nuclear disarmament talks with the North. Trump also said the nuclear negotiations with North Korea have been hampered by a lack of support from China, which is the North’s only major ally and is engaged in an intensifying trade dispute with the United States.

The Chinese foreign ministry blasted Trump’s comments.

“The U.S. statement violates basic facts and is irresponsible,” the ministry said online. “We are seriously concerned about it and have made solemn representations to the U.S. side.”

Meanwhile, while describing the postponement of Pompeo’s trip as a setback, South Korea’s Foreign Ministry said it expects China to continue serving a “constructive role” in international efforts to solve the nuclear crisis and noted that Beijing continues to express commitment to fully implement sanctions against the North.

“It’s most important to maintain a long-term view while maintaining a momentum for dialogue and concentrate diplomatic efforts to faithfully implement the agreements from the summits between South Korea and North Korea and between North Korea and the United States, instead of attaching meaning to each change in the situation,” the ministry said.