SEOUL - Park Geun-hye, president of the Republic of Korea (ROK) denounced the Democratic People's Republic of Korea (DPRK)'s fifth nuclear test during her trip to Laos, calling it as "fanatic recklessness," her office said Friday.

Park, who has stayed in the Laotian capital of Vientiane to attend the East Asia Summit (EAS), said that the DPRK conducted a second nuclear test this year following the January test, strongly criticizing it as a clear violation of UN Security Council resolutions and a grave challenge to the international society.

The ROK's president said the DPRK's nuclear test proves the "fanatic recklessness" of Pyongyang adhering to nuclear development in a thorough defiance of the international community's unified will not to accept the DPRK's nuclear program.

Her denunciation followed the DPRK's fifth nuclear test Friday morning at its main Punggye-ri test site. Seoul's military said artificial seismic waves were detected from a 5.0 magnitude quake close to Punggye-ri, where the fourth nuclear detonation was carried out in January.

South Korea regards the latest test as the most powerful as the 5.0 magnitude can put its estimated explosive yield at about 10 kilotons.

Six kilotons of explosive yield were spotted from the fourth test.

The DPRK's state media announced it has successfully carried out "nuclear warhead explosion" test, saying this test showed its capability of mounting nuclear warhead on ballistic missiles.

Pyongyang had claimed it already possessed a technology of miniaturizing nuclear warhead small enough to fit on ballistic missiles that can reach the US mainland.

Since top DPRK leader Kim Jong Un gave an order on March 15 to test a nuclear warhead and ballistic rockets capable of carrying the warhead "in a short time," the DPRK has conducted a series of ballistic missile launches including ground-based ballistic missiles and submarine-launched ballistic missiles (SLBM).

President Park decided to return to ROK some four hours earlier than scheduled, right after holding a bilateral summit with Laotian counterpart.

What Pyongyang can gain from nuclear tests, Park said, would only be the international society's tougher sanctions and isolation. She said this provocation would speed up its self-destruction.

The president said her government will push for additional harsher sanctions, both bilateral and multilateral in UN Security Council, in cooperation with the international society, vowing to strengthen pressures on Pyongyang with all available measures to make it give up its nuclear program.

President Park made a phone call with US President Barack Obama, agreeing to take all available measures including fresh tougher sanctions in UN Security Council, according to Park's office. The United States, ROK and Japan asked for an emergency meeting of UN Security Council to address the DPRK's fresh nuclear detonation.

Cheong Wa Dae announced a separate statement of the government, urging Pyongyang to immediately dismantle its nuclear and missile programs in a complete, verifiable and irreversible manner.

Chairman of ROK's Joint Chiefs of Staff (JCS) convened an emergency video conference with field commanders to review defense readiness against possible provocations from the DPRK. The JCS head ordered a stern, strong retaliation against any DPRK provocation.