SINGAPORE/SEOUL -- US and North Korean officials are set to meet in Singapore on Tuesday to discuss security and protocol issues concerning a possible summit between their leaders, a diplomatic source here said.

White House Deputy Chief of Staff for Operations Joe Hagin leads the US delegation, while Kim Chang-son, a senior official at the State Affairs Commission, represents the North. They arrived in the city state on Monday.

The high-stakes summit between US President Donald Trump and North Korean leader Kim Jong-un over Pyongyang's denuclearization is expected to take place in Singapore on June 12.

Trump called it off on Thursday, citing "open hostility" from the North. But following Pyongyang's conciliatory gesture and Seoul's mediation, Trump suggested that the summit could go ahead as planned.

"I understand that the two sides will meet in Singapore on May

29 and hold consultations over such practical issues as the concrete summit date, venue, protocol and security," the source said, declining to be named.

The planned talks in Singapore are running in parallel with separate consultations at the inter-Korean border village of Panmunjom.

At Panmunjom, the two sides have reportedly been discussing denuclearization methods and timelines, as well as ways to ensure the reclusive state's regime security.

The delegations are led by Ambassador Sung Kim, a former chief US nuclear envoy, and North Korea's Vice Foreign Minister Choe Son-hui.

Kim, along with his staff, was seen leaving his Seoul hotel in a diplomatic sedan in the morning, raising speculation that he could resume talks with the North following the first round on Sunday.

Observers say that after the working-level talks, Kim Yong-chol, a vice central committee chairman of the North's ruling Workers' Party, and US Secretary of State Mike Pompeo could meet for final consultations, possibly in Washington.

It remains unclear how much progress the two sides have made in their efforts to bridge gaps over the denuclearization method.

Washington has called for a swift, stringent denuclearization approach to prevent the communist regime from stringing out negotiations and wringing out undue benefits. Pyongyang favors a gradual drawdown of its nuclear program, with benefits flowing in along the way.

In a phone call on Monday, Trump and Japanese Prime Minister Shinzo Abe affirmed the "shared imperative of achieving the complete and permanent dismantlement of North Korea's nuclear, chemical, and biological weapons and ballistic missile programs."

It was yet another indication of Washington's tough stance on the denuclearization front.

But Trump has repeatedly held out the prospect of economic incentives to lure a hesitant Pyongyang into the denuclearization process.

"I truly believe North Korea has brilliant potential and will be a great economic and financial Nation one day. Kim Jong Un agrees with me on this. It will happen!" Trump said in a Sunday tweet.

Washington has also sought to reassure the communist regime that its security will be preserved even after its disarmament.

"(The North Korean leader) and I spoke about what assurances are going to be provided to him. These are assurances that would clearly have to be capable in the same way we are demanding a permanent, irreversible denuclearization ... verifiable denuclearization," Secretary of State Pompeo told a congressional session last week.

The secretary also hinted that the US government would seek to gain parliamentary approval for any deal to make it permanent.

"It is our intention to achieve an agreement that would be put before the United States Senate. That is our goal," Pompeo said.

Pyongyang has apparently been wary that any deal could be reversed following a change of government in the US, as seen in Trump's moves to undo the multilateral nuclear deal with Iran clinched under his predecessor Barack Obama.(Yonhap)