UPDATE 5-U.S.' Pompeo hails 'significant' North Korea progress; experts sceptical

(Corrects 4th paragraph to make clear that Washington has been seeking inspection of Yongbyon. North Korea has offered conditionally to close the site, but has not made a public comment on its inspection.)

* Pompeo says inspectors to visit nuclear, missile test sites

* Says 'pretty close' to agreement on second summit

* Upbeat tone from N.Korea a change from last Pompeo visit

* Kim expected to visit Russia, Xi to N.Korea soon -Seoul

By Hyonhee Shin and David Brunnstrom

SEOUL/WASHINGTON, Oct 8 (Reuters) - U.S. Secretary of State Mike Pompeo on Monday hailed "significant progress" in talks with North Korean leader Kim Jong Un at the weekend and said the sides were "pretty close" to agreeing details for a second summit between Kim and President Donald Trump.

However, experts questioned what Pompeo had achieved on Sunday on his fourth visit to Pyongyang this year. They said the North Korean leader appeared simply to be repackaging and dragging out past pledges.

Pompeo told reporters Kim had said he was ready to allow international inspectors into North Korea's Punggye-ri nuclear testing site and the Sohae missile engine test facility as soon as the two sides agreed on logistics.

However, Pompeo declined to say whether there had been any movement on North Korea allowing inspectors to visit its Yongbyon site, which produces fuel for nuclear weapons, as the United States has sought. North Korea has said it could permanently close Yongbyon if Washington took "corresponding measures," of which there has so far been no sign.

In May, North Korea blew up tunnels at Punggye-ri and called this proof of its commitment to end nuclear testing, but a senior White House official accused Pyongyang at the time of breaking a promise to allow experts to witness dismantlement of the site, which meant there was no one there to verify what actually occurred.

Pompeo did not say when inspectors would be allowed to Punggye-ri, and the State Department did not respond when asked if they would be Americans or others from international nuclear bodies.

"There's a lot of logistics that will be required to execute that," Pompeo told a news briefing in Seoul before leaving for Beijing, where the frosty tone of talks will raise worries about China's willingness help maintain a tough U.S.-led sanctions regime on North Korea.

"SELLING THE SAME HORSE TWICE"

Experts said the offer on inspections amounted to dressing up of an old, unfulfilled pledge as a new concession.

"The real takeaway from this Punggye-ri pledge is that Kim has mastered the art of milking a single cosmetic concession for months to burn clock," Vipin Narang, an associate professor of political science at the Massachusetts Institute of Technology, said on Twitter.