Foreign Minister Yun Byung-se met with the U.S. ambassador to Seoul and the commander of the U.S. Forces Korea on Wednesday to discuss North Korea's claims of a successful hydrogen bomb test.

Amb. Mark Lippert and USFK commander Gen. Curtis Scaparrotti arrived at the Foreign Ministry building for talks with Yun hours after the North announced the test had taken place earlier in the day.

It is the North's fourth nuclear test following those in 2006, 2009 and 2013.

Yun, who attended an emergency security meeting presided over by President Park Geun-hye earlier in the day, is expected to hold phone talks with his counterparts in the U.S., Japan and China, among other nations, according to a ministry official.

"Considering the nature of the issue, a phone call is urgent" between Yun and U.S. Secretary of State John Kerry, the official said, adding that the allies have been in talks to set a time.

"The U.S. Embassy in Seoul and the South Korean Embassy in Washington are in full operation," he said. "Since the possibility of a nuclear test was raised, we have been sharing information and assessments and working together."

The ministry has been put on an emergency footing and working closely with relevant government departments and international organizations, according to another official. (Yonhap)