NAYPYITAW (Yonhap) -- The foreign ministers of South Korea and China on Friday vowed to work together in easing tension on the Korean Peninsula, saying that North Korea's recent missile launches pose a grave threat to peace and stability in the region, a Seoul official said.

South Korean Foreign Minister Yun Byung-se met with his Chinese counterpart Wang Yi earlier in the day on the sidelines of the ASEAN Regional Forum (ARF), Asia's biggest security forum, slated for Sunday.

"The two foreign ministers reaffirmed zero tolerance against the North's nuclear weapons program," said an official at Seoul's foreign ministry, asking not to be named.

"Yun stressed that the North's missile launches are posing a serious threat to peace and stability on the peninsula and in Northeast Asia, calling for Pyongyang to halt its provocative acts," he added.

The remarks came as the North has ratcheted up tensions on the Korean Peninsula by firing off a series of short-range missiles and rockets in recent weeks and threatening a fourth nuclear test.

Yun said that the money Pyongyang has recently spent on missile launches is equivalent to the combined annual salaries of about 53,000 workers at the inter-Korean industrial complex in the North's border city of Kaesong.

Seoul and Beijing plan to strengthen cooperation in easing tension on the peninsula and make efforts to hold meaningful and practical talks on curbing the North's nuclear threat, according to the official.

The Seoul-Beijing meeting came about one month after South Korean President Park Geun-hye and her Chinese counterpart Xi Jinping held a summit in Seoul, during which they reaffirmed "firm" opposition to North Korea's nuclear weapons program.

Xi's visit to Seoul was made before his trip to North Korea, China's long-time ally, in an unprecedented move seen as reflecting China's disapproval of the North's last nuclear test in February 2013.

With Seoul seeking to drum up support from member countries to the ARF to counter the North's belligerent behavior, top diplomats from 26 Asia-Pacific countries and the European Union are scheduled to gather together for the ARF and other ASEAN talks.

The ARF draws all members to the six-party talks aimed at ending the North's nuclear weapons program.

When asked about a possible meeting with North Korea, the Chinese envoy told a group of reporters that a final decision has not been made, adding there is not enough time to arrange a meeting.

Hong Lei, a spokesman at China's foreign ministry, added that "We are open (to such talks)."

North Korea's new foreign minister Ri Su-yong is expected to arrive in Naypyitaw on Saturday after visiting Laos and Vietnam, according to officials. He will make his debut at the ARF after becoming the North's top diplomat in April.

North Korea's nuclear weapons, territorial disputes in the South China Sea and the Ukraine crisis are likely to top the agenda for this year's regional forum, Seoul officials said.