Who will cough up for lodgings at the five-star Fullerton Hotel, believed to be the North Korean leader's preferred option, is one of many reported logistical and protocol headaches surrounding this month's meeting between Kim and US President Donald Trump.

The United States is prepared to pay but fears offending cash-poor but pride-rich North Korea, the Washington Post wrote last week.

The International Campaign to Abolish Nuclear Weapons (ICAN) said it was willing to help resolve the impasse by bankrolling Kim's delegation, using part of the $1.1 million cash prize it received for winning last year's Nobel Peace Prize.

"We are ready to shoulder the cost of the summit, naturally including expenses for accommodation and conference venues," Akira Kawasaki, an ICAN representative in Japan, told AFP.

"If holding the summit is in danger because of financial problems, we are ready to shoulder the cost as it is an important, historic meeting," he added.

Kawasaki declined to say how much ICAN could stump up but said part of the Nobel Prize award would be put to the summit "in order to support peace in the Korean peninsula and a nuclear weapon-free world".

The sum would be negotiated if North Korea accepted the offer, he said.

The presidential suite at the Fullerton boasts, according to its website, a baby grand piano and claims to be "the most exclusive hotel suite in Singapore."

With a private elevator offering exclusive access, the suite is 201 square metres (2,164 square feet) and reportedly costs more than $6,000 for one night.

Reporters camped outside the hotel last week to catch a glimpse of Kim Chang Son, Kim's de facto chief of staff, who travelled to Singapore to lay the groundwork for the June 12 summit.

The Singapore dialogue will be the first time a sitting US president has met a North Korean leader.

Talks are expected to focus on denuclearisation of the Korean peninsula and improving relations between Washington and Pyongyang.