US President Donald Trump met Vietnam's president, Nguyen Phu Trong, in Hanoi on Wednesday, hours before Trump was due to meet North Korean leader Kim Jong Un for their second summit.

Trump and Trong, who is also general secretary of the ruling Communist Party, met at the grand, colonial-era presidential palace. Trump was later due to have lunch with Prime Minister Nguyen Xuan Phuc.

On Wednesday evening, Trump is scheduled to meet Kim at the city's Metropole hotel, eight months after their first summit in Singapore, to discuss efforts to get North Korea to dismantle its nuclear weapons programme.