South Korea's President Moon Jae-in expressed deep regret over US President Donald Trump's decision to cancel a June 12 summit with North Korea's leader Kim Jong-un.
At an emergency meeting on Thursday, Moon told his top security officials he was "very perplexed" and found it "very regrettable that the North Korea-US summit will not be held on June 12", according to Seoul's presidential office.
Moon urged "more direct and close dialogue" between Trump and Kim, adding denuclearisation of the Korean Peninsula should not be delayed by the decision to call off the summit.
Trump blamed "anger" and "hostility" from North Korea when he cancelled the widely anticipated meeting, which was aimed at ridding Pyonyang of its nuclear weapons.
The decision came a day after North Korea attacked US Vice President Mike Pence as "ignorant and stupid".
Singapore, which was to host the historic summit, said it also "regrets" the cancellation.
In a Twitter post, the country's foreign ministry said it hoped "efforts to find lasting peace and stability on the Korean Peninsula will continue".
Antonio Guterres, UN secretary-general, said he was "profoundly worried" over Trump's decision.
"I am deeply concerned by the cancellation of the planned meeting in Singapore between the president of the United States and the leader of the Democratic People's Republic of Korea," Guterres said at the University of Geneva on Thursday.
He urged the parties to demonstrate "nerves of steel so that we can ... [obtain] an objective we all share: the verifiable and peaceful denuclearisation of the Korean Peninsula".
The secretary-general's remarks came at a ceremony to present the UN's new agenda on disarmament.
He said the events of the day show "the importance of disarmament", adding 15 000 nuclear weapons remain in stockpiles around the world.
The United Kingdom also expressed disappointment with Trump's decision, with a spokesperson for Prime Minister Theresa May calling for an agreement to "bring about the complete, verifiable and irreversible denuclearisation of the Korean Peninsula".
Britain will continue to work with its partners to that end, the spokesperson added.
