Manila: Officials have expressed alarm over North Korea’s detonation of a nuclear bomb on Sunday as they said recent muscle flexing by Pyongyang could have serious implications for thousands of Filipinos in the Korean peninsula.

Although Manila lies 2,795 kilometres from the North Korean capital, Pyongyang, Kristoffer James Purisima, Deputy Administrator of the Office of Civil Defence said Philippine officials are deeply concerned over the safety of Filipinos in the Korean peninsula.

He said there are an estimated 65,000 Filipinos living and working in South Korea and a possible attack by North Korea on its traditional nemesis, South Korea, would be a major humanitarian concern.

At the same time, civil defence officials are considering various scenarios in the event that a nuclear missile strike by North Korea would target the US trust territory in Guam, which is home to one of the largest American military bases outside of continental United States.

“We are holding meetings today on how to best provide protection for our compatriots,” Purisima said.

On Sunday, North Korea detonated what was reported to be a 50 kiloton hydrogen bomb in Punggye-ri. The explosion, believed to have been detonated underground, was powerful to cause a minor earthquake.

North Korea had spent years developing its nuclear capabilities. But while it had the facility and know-how to manufacture a nuclear bomb, its technology lagged in coming up with delivery systems for its nuclear warheads.

In recent years it was able to develop rockets powerful enough carry payloads thousands of kilometres and nuclear warheads small enough to be fitted on a warhead but powerful enough to devastate small cities.

“We are gravely concerned over this hydrogen bomb testing by the Democratic People’s Republic of Korea (DPRK),” Philippine Foreign Affairs Secretary Alan Peter Cayetano said on Sunday. “Such provocative actions undermine regional peace and stability.”

Cayetano is in Seoul on an official visit, issued the statement shortly after Pyongyang announced that it tested a hydrogen bomb at its Punggye-ri nuclear test site.

“Aside from flouting all of its commitments under relevant United Nations Security Council resolutions, this test limits our available options for meaningful dialogue to address the real issues confronting the Korean Peninsula,” Cayetano adds.

“The Philippines urges the DPRK to return to the negotiating table,” he said, adding that the regional bloc, the Association of Southeast Asian Nations (Asean) is ready to play a role “in creating diplomatic space to effect meaningful dialogue.”

Cayetano, currently serves as chair of the Asean.

Cayetano likewise met with some 300 members of the Filipino community in Seoul and assured them that measures are in place to make sure Manila could come to their assistance in case it would become necessary for them to evacuate.

The detonation in Punggye-ri came a few days after the DPRK launched a ballistic missile that flew over the northern Japanese island of Hokkaido, prompting Tokyo to issue a missile launch warning to its citizens.

It also came a few days after Pyongyang announced more missile test launches.