US President Donald Trump on Monday met Singaporean Prime Minister Lee Hsien Loong and thanked him for hosting his upcoming summit with North Korean leader Kim Jong-un, saying he appreciated the hospitality, professionalism and friendship.

"We have a very interesting meeting in particular tomorrow (Tuesday), and I think things can work out very nicely," The Straits Times quoted Trump as saying.

"But we appreciate your hospitality and professionalism and your friendship. Thank you very much," the President added.

The two leaders shared a warm handshake at the Istana or presidential palace before they began their working lunch.

During the meeting, the officials also celebrated Trump's birthday. He will turn 72 on June 14.

Foreign Minister Vivian Balakrishnan posted a photo on social media of Trump posing with the birthday cake.

"Celebrating birthday, a bit early," he wrote.

Trump is also scheduled to have a meet-and-greet session with US embassy staff and American military officers at the Shangri-la Hotel later on Monday, The Straits Times reported.

Trump and his delegation including National Security Adviser John Bolton, Secretary of State Mike Pompeo and White House Press Secretary Sarah Huckabee Sanders landed in Singapore's Paya Lebar Air Base on Sunday night, after attending the G7 Summit in Canada.

Also on Sunday, Kim arrived in Singapore aboard an Air China plane. This is his first-known trip outside Northeast Asia since taking power in 2011.

Trump and Kim's summit, the first ever between two sitting leaders of the countries, will begin at 9 a.m. on Tuesday at the exclusive Capella Hotel in Sentosa Island.

Meanwhile on Monday, senior North Korean and US diplomats held last-minute talks in Singapore to come up with a draft agreement to be presented to the leaders of the two countries during their summit, reports Yonhap News Agency.

Ambassador Sung Kim, the US State Department's top Korea expert, met Choe Son-hui, the North's Vice Foreign Minister, at the Ritz Carlton hotel.

Choe and Kim have already held several rounds of discussions at Panmunjom on the inter-Korean border that were reportedly focused on summit agenda items, including denuclearisation and security assurance measures.