VIENNA (Reuters) - The world’s main nuclear test-ban body stands ready to verify North Korea’s closure of its test site but it has yet to be asked and the process would take weeks rather than days, its chief said on Wednesday.

North Korea, which is believed to have tested six atom bombs, has said it will dismantle its only known nuclear test site this month ahead of a meeting on June 12 between U.S. President Donald Trump and North Korean leader Kim Jong Un.

Pyongyang has invited international media to witness the dismantling of the Punggye-ri site sometime between May 23 and May 25 but not technical experts, even though the United States has called for “a permanent and irreversible closure that can be inspected and fully accounted for”.

“We have the technology to verify any agreement linked to the closure of the test site,” the head of the Comprehensive nuclear Test-Ban Treaty Organization (CTBTO), Lassina Zerbo, told reporters, although it has received no request to do so.

That technology includes seismic sensors that could be deployed around the site, and ground-penetrating radar to determine what had happened to the tunnels there, Zerbo said, declining to provide an exhaustive list.

The two-day window given for reporters to observe the closure would be too short for verification, he said, warning against taking a carefully choreographed ceremony at face value.

“As an international organisation I shouldn’t be into a show because my job is to serve the international community... not to just do a show to say that we’ve been there. That doesn’t bring me anything,” Zerbo said.

But verification could be achieved in time for the summit, he added.

“There’s a lot of things we can do in two weeks. But we cannot do something on the 23rd (of May) to finish and certify on the 23rd,” he said.

The Comprehensive nuclear Test-Ban Treaty has been signed by 183 countries and ratified by 166. But to come into effect it must be ratified by eight remaining so-called Annex 2 states, including North Korea and the United States as well as Israel, Iran, India and Pakistan.

The CTBTO runs a global network of monitoring stations that use seismic and other technology to detect nuclear explosions like North Korea’s recent tests. That equipment also shows North Korea has yet to blow up the tunnels at Pyunggye-ri, Zerbo said.

“To date, we haven’t heard any noise that is linked to the blow of a tunnel in the vicinity of the test site,” he said.