Seoul -- North Korea has almost completed rebuilding a long-range rocket site it had promised to close, South Korean lawmakers told reporters on Friday after a closed-door meeting with intelligence officials in Seoul. The claim comes a month after a second summit between President Donald Trump and North Korean leader Kim Jong Un in February ended without an agreement, deepening a gap between the two on how to achieve Mr. Trump's stated goal of "complete denuclearization."

Shortly after the end of the Hanoi summit, a series of satellite images emerged suggesting increased activity at the North's Sohae rocket site, triggering international alarm that the nuclear-armed state might be preparing a long-range or space launch.

"The North began rebuilding the center, which was partly dismantled last July, before the North-U.S. summit in February," lawmaker Kim Min-ki told reporters after the closed-door briefing by the National Intelligence Service.

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"The work is almost complete with some maintenance activity being underway," he said.

North Korea leader Kim Jong Un smiles as he visits Sohae Space Center in Cholsan County,North Pyongan province for the testing of a new engine for an intercontinental ballistic missile (ICBM) in this undated photo released by North Korea's Korean Central News Agency (KCNA) on April 9, 2016. REUTERS/KCNA

North Korea has been banned by the UN Security Council from carrying out space launches, as some of its technology was similar to that used for intercontinental ballistic missiles, or ICBMs.

But earlier this month the Washington-based Center for Strategic and International Studies (CSIS) said there was "deliberate and purposeful" activity going on at the Sohae rocket site.

Friday's latest assessment by Seoul could suggest a reversal in policy by Kim, who agreed to shut the Sohae site at a meeting with South Korean President Moon Jae-in in Pyongyang last year.

Experts have suggested the Kim regime might be trying to convey its displeasure over the breakdown of the Hanoi nuclear summit with the renewed work at Sohae, but the Trump administration made it clear earlier this month that it doesn't necessarily agree with the public analysis, and it still believes its goal of denuclearizing North Korea is attainable during Mr. Trump's first term.

The White House noted that the activity at Sohae had been noticed even before the Hanoi summit, a notion seemingly confirmed on Friday by the South Korean intelligence assessment. A Trump administration official speaking in early March added, however, that it would represent backsliding by North Korea if the regime was to start using the facility again in any capacity, because they had agreed to dismantle it. A new satellite launch would be, in the administration's view, "inconsistent with the commitments the North Koreans have made."

A commercial satellite image taken over Tongchang-ri, North Korea on March 2, 2019 and released March 5, 2019 shows apparent rebuilding work at the Sohae Satellite Launching Station launch pad, according to researchers of Beyond Parallel, a CSIS project HANDOUT/REUTERS

Experts have warned that a new launch of any kind would send the stuttering talks on denuclearization into disarray. Moon Chung-in, the South Korean presidential special advisor on national security, said the outcome would be "catastrophic."

The nuclear-armed state is also "operating uranium enrichment facilities" at its Yongbyon nuclear complex, the lawmaker added.

In the aftermath of the Hanoi summit, Pyongyang and Washington have both sought to blame the other's intransigence for the deadlock.

Pyongyang said it had proposed dismantling the Yongbyon complex -- a sprawling site covering multiple different facilities -- in exchange for the lifting of economic sanctions that have strangled and isolated the North.

But U.S. officials have said it was not clear exactly which facilities at the Yongbyon complex the North was willing to give up, while Mr. Trump has said that "the weapons themselves need to be on the table."