DPRK's nuclear test strongly opposed

People at a railroad station in Seoul watch a news report on Wednesday after the Democratic People's Republic of Korea announced that it had conducted its first hydrogen bomb test. JUNG YEON-JE/AFP

Beijing urges neighbor 'to halt actions that will deteriorate the situation'

Countries and international organizations said they were still examining the test's details and impact, since some key facts were believed missing in the official statement released through the Korean Central News Agency in Pyongyang.

The nuclear test, the fourth by the DPRK, was conducted at a site close to the Chinese border. Previously, the DPRK conducted three nuclear tests－in 2006, 2009 and 2013－drawing fierce international objections and sanctions.

On Wednesday morning, the China Earthquake Network Center said a magnitude-4.9 quake jolted the DPRK at 9:30 am Beijing time "at a depth of 0 km".

Then the state-run Korean Central News Agency said DPRK top leader Kim Jong-un had ordered the hydrogen bomb test on Dec 15 and signed the final order on Sunday. The test was a "total success" and was conducted "in a safe and perfect manner", it said.

In response, Beijing issued a rare written statement in the afternoon, in which the Foreign Ministry said: "We strongly urge the DPRK to honor its denuclearization pledges and stop taking any action that will deteriorate the situation."

China's Ministry of Environmental Protection is "monitoring the data and will conduct an all-out radiation emergency test in the border area", Foreign Ministry spokeswoman Hua Chunying said.

By 1 pm, local readings of gamma radiation had been normal, the environmental ministry said.