WASHINGTON -- The United States appears to be reviewing various options for the success of denuclearization negotiations with North Korea, Seoul's unification minister said Monday.

Kim Yeon-chul made the remark to reporters after meeting with US Special Representative for North Korea Stephen Biegun in Washington. He declined to elaborate.

Denuclearization negotiations between Washington and Pyongyang have stalled since February's second summit between US President Donald Trump and North Korean leader Kim Jong-un ended without a deal.

The North has threatened to seek a "new way" unless the US comes up with an acceptable offer before the end of the year.

"The US appears to be reviewing various options for the success of these negotiations," the minister said. "It's a sensitive period, so I'd rather not speak in detailed terms."

The minister was answering a question about North Korea's latest statement rejecting talks with the US.

Kim Yong-chol, a former nuclear negotiator for Pyongyang, said earlier Monday that the US "should not even dream of" having denuclearization negotiations with the North before it withdraws its "hostile" policy.

He also scoffed at Sunday's decision by South Korea and the US to postpone combined military exercises in support of diplomatic efforts to denuclearize the North, saying Pyongyang wants them stopped completely.

The minister, who oversees inter-Korean relations, said he and Biegun had candid and wide-ranging discussions on the current state of South-North ties, including the issue of the now-suspended tourist resort on North Korea's Mount Kumgang.

North Korea has threatened to tear down all South Korean-built facilities at the resort, saying it will establish its own tourism zone there.

The US has been reluctant to support full-fledged inter-Korean economic activity out of concern it could undermine international sanctions on Pyongyang.

"We explained our ideas on the Mount Kumgang tourism project, as well as other inter-Korean issues," Kim, the minister, said.

"There are many areas that need to be discussed. ... I believe we will have another opportunity to have such discussions soon."

Kim is scheduled to deliver a keynote address at a forum in Washington on Wednesday. (Yonhap)