The narrow road to the compound, the temporary home to the US officials, remained blocked by security guards. A security official cited an "important private event" there.

The two sides are in Singapore apparently to discuss the logistical details of the summit talks between the North's leader Kim Jong-un and US President Donald Trump that will likely take place in Singapore later this month.

"They appear to be waiting for additional instructions from their governments, as Kim Yong-chol. vice chairman of the Workers' Party's Central Committee, is on a visit to the US," a diplomatic source said.

On the other side of this city state, the defense chiefs of Asia-Pacific and European countries were set to convene an annual security forum, called the Shangri-La Dialogue.

South Korean Defense Minister Song Young-moo began his trip to Singapore earlier Friday and the Pentagon chief, Jim Mattis, was also seen entering the venue, the Shangri-La Hotel.

Police, armed with rifles and pistols, conducted road blocks and stringent security checks around the hotel.

The hotel is among the top candidates to host the Kim-Trump meeting, given its history of serving as the stage for a number of major meetings and its location minutes away from bustling streets.

In 2015, Chinese President Xi Jinping and his Taiwanese counterpart Ma Ying-jeou held a landmark summit at the hotel.

A South Korean resident in Singapore said, "Many think it's natural that the Shangri-La Hotel will become the venue. Singapore is a globally hot tourist spot. Taking security and safety measures is not an easy matter for other major hotels. In that sense, Shangri-La is a good place."

If North Korea and the US have the Shangri-La in mind, the three-day security forum to last through Sunday at the hotel can be a last-minute test of security conditions.

The hotelier at the nearby Orchard Hotel, however, said the Istana, the official residence and office of the Singaporean president, is a better choice, adding it's easier to "manage the situations" there.

A local taxi driver said: "I know about the talk of the US-North Korea summit in Singapore. I am a bit worried about the possibility of a terrorist attack in Singapore because of it." (Yonhap)