The picture posted online by Vivian Balakrishnan as the group toured a series of major sites, less than 12 hours ahead of Kim's meeting with US President Donald Trump, is the first such public image of the North's leader.

In his own country, his appearances are normally carefully managed, with any foreigners present having to go through hours-long security checks beforehand.

Kim had remained inside his Singapore hotel all day but a lengthy motorcade emerged from the St Regis in the evening, a North Korean flag flying from his stretch limousine.

The convoy pulled into the Gardens by the Bay, a man-made park spanning 101 hectares (250 acres) along Singapore's waterfront that features two air-conditioned domes containing plants native to temperate climates.

Kim was spotted walking inside, with his sister and close aide Kim Yo Jong also part of the group.

Minutes later, Balakrishnan tweeted his picture of himself with the North Korean leader and the city-state's education minister. "#Jalanjalan," he wrote -- a colloquial expression meaning "going for a stroll".

Some commenters approved. "So cute!" said one.

Others were distinctly unimpressed.

North Korea stands accused of widespread human rights abuses and user @huangyonghua asked Balakrishnan: "Is it worth taking a picture with a tyrant? It's your shame."

Several posters believed it was the first time a selfie with Kim had been publicly seen.

"I had to view this several times before even grasping this was real," posted Oxford University Chinese studies postgraduate Tom Fowdy.

- 'Nocturnal bird's eye view' -

At the Marina Bay Sands (MBS) hotel, casino and convention centre, Kim visited the high-level SkyPark that links the three 55-storey towers of the complex.

The North's state-run KCNA news agency suggested the Swiss-educated leader -- who has barely left his country since succeeding his father in 2011 -- was impressed by what he saw as he enjoyed "a nocturnal bird's eye view" from the top of the luxury resort.

"He said Singapore is clean and beautiful and every building is stylish as he heard of in the past, adding he is going to learn a lot from the good knowledge and experience of Singapore in various fields in the future," the KCNA report added.

Later he walked halfway over the Jubilee Bridge, built in 2015 to mark Singapore's 50th year, where the group paused for his escorts to take more selfies, as Kim grinned and waved.

Police guarding metal barricades held back around 60 journalists and cameramen, their flashes firing.

The structure offers a view of Singapore's iconic skyline, flanked on one side by the MBS, and the towering skyscrapers of the business district on the other.

The glittering lights will have been a striking contrast to his often dimly lit capital Pyongyang, much of which is tired even though Kim has overseen the construction of several prestige projects.