SEOUL (REUTERS, AFP) - North Korea on Thursday (May 24) issued a new threat to walk away from the planned Trump-Kim summit, scheduled for June 12 in Singapore, saying the future of the summit is "entirely" up to the US.

North Korea's vice-foreign minister Choe Son Hui, a longtime nuclear negotiator, said her country will reconsider the planned summit with the United States if Washington sticks to "unlawful and outrageous acts".

She condemned a media interview by US Vice-President Mike Pence in which he compared the North to Libya.

It was the second time Pyongyang is threatening to reconsider the high-stakes summit. North Korea's first vice-foreign minister Kim Kye Gwan last Wednesday (May 16) threatened to scrap the summit if Pyongyang was pushed toward "unilateral nuclear abandonment".

Trump is due to meet his North Korean counterpart Kim Jong Un in Singapore on June 12 for high stakes talks aimed at ridding the reclusive state of its newly acquired nuclear weapons and improving ties after decades of animosity.

The summit announcement came after months of unusually cordial diplomacy between the historic foes brokered by South Korea.

But the newfound bonhomie and the meeting's potential success has been thrown into doubt in recent days with both Washington and Pyongyang raising the prospect of cancelling the talks and trading threats.

Politically, Trump has invested heavily in the success of the planned summit, and so privately most US officials, as well as outside observers, believe it will go ahead. Hand-picked aides - including deputy chief of staff Joe Hagin and deputy national security adviser Mira Ricardel - are travelling to Singapore, officials said.

They are expected to meet their North Korean counterparts and iron out details of the meeting.

Some analysts have suggested both sides still want to meet in Singapore but are playing hardball in the run up to the summit. "It's to increase leverage at negotiations," Koh Yu Hwan, a professor of North Korean Studies at Dongguk University, told AFP.

"Both sides are sending signals that they want it (the summit) and that they want it to go well."

In a statement carried by the Korean Central News Agency (KCNA) on Thursday (May 24), Choe, a longtime nuclear negotiator, said that whether the June 12 summit between its leader Kim Jong Un and US President Donald Trump will happen as scheduled entirely rests on the decision and behaviour of the US.

She said the North was ready for a "nuclear-to-nuclear showdown" if the US didn't change its approach to the disarmament talks.

"Whether the US will meet us at a meeting room or encounter us at nuclear-to-nuclear showdown is entirely dependent upon the decision and behavior of the United States," Choe said.

"In case the US offends against our goodwill and clings to unlawful and outrageous acts, I will put forward a suggestion to our supreme leadership for reconsidering the DPRK-US summit," she added.

"We will neither beg the US for dialogue nor take the trouble to persuade them if they do not want to sit together with us," said Choe.

She slammed Pence on Thursday for "ignorant and stupid" remarks he made in a recent media interview about upcoming denuclearisation talks.

"I cannot suppress my surprise at such ignorant and stupid remarks gushing out from the mouth of the US vice-president," she said in the statement released by KCNA.

Mr Pence said on Monday: "There was some talk about the Libyan model last week, and you know, as the President made clear, this will only end like the Libyan model ended if Kim Jong Un doesn't make a deal."

When it was noted that the comparison could be interpreted as a threat, Pence told Fox News: "Well, I think it's more of a fact."

Pence said North Korea should not attempt to seek concessions from the United States for promises it did not intend to keep.

"It would be a great mistake for Kim Jong Un to think he could play Donald Trump," Mr Pence said according to excerpts of an interview made available by Fox.

When asked if Mr Trump could still walk away from the summit scheduled for June 12 in Singapore, Pence replied: "Well there's no question."