Top nuclear envoys of South Korea and the United States agreed on the need for "swift" and "tough" measures against North Korea, promising to closely cooperate in making Pyongyang give up its pursuit of weapons of mass destruction, Seoul's foreign ministry said Friday.

Kim Hong-kyun, special representative for Korean Peninsula Peace and Security Affairs at the foreign ministry, held talks with his U.S. counterpart Sung Kim via phone and exchanged views on necessary steps in response to the North's nuclear test earlier in the day, according to the ministry.

"The two shared the view that it is necessary to take swift and strong action through the Security Council, while agreeing to closely cooperate in (seeking) stronger sanctions including additional measures at the bilateral level," the ministry said.

They also agreed to have a more "in-depth" discussion on the North's latest nuclear test and its ramifications when they meet in Seoul on Tuesday next week, it added.

A magnitude-5 earthquake was detected at the North Korea's nuclear test site in its northeastern region at around 9:30 a.m. The North later confirmed that it has successfully conducted a nuclear detonation test.

This marked the North's fifth nuclear test following the last one in January that drew condemnation from the international community and led the United Nations Security Council to adopt the toughest-ever resolution in March. Pyongyang also carried out nuclear tests in 2006, 2009 and 2013.

During the meeting with the parliament's diplomacy committee, Kim also said the government cannot rule out the possibility that Pyongyang will conduct a sixth nuclear test soon.

"The government acknowledges that it failed to stop the development of North Korean nukes despite making various efforts. There will be various reviews on the matter," Kim added, when suggested that Seoul should come up with a new strategy by lawmakers.

"Amid the escalating gravity of the situation, we will seek to impose further pressure on North Korea and induce them to change course when the United Nations agrees to hand down more sanctions," Kim also said.

The envoy added that Kim Jong-un currently aims to win the status as nuclear-armed nation, although the international community is unlikely to make such a concession.

Kim said parliament should set up a special commission to discuss the North Korean issue, rather than continue quarreling over the deployment of an advanced U.S. missile system in the country. The opposition parties have expressed reservations about the Terminal High Altitude Area Defense system that Seoul and Washington want in place by the end of 2017. (Yonhap)