US Secretary of State Pompeo, N Korea minister Ri shake hands

U.S. Secretary of State Mike Pompeo and North Korean Foreign Minister Ri Yong Ho shook hands and exchanged words and smiles at a Southeast Asian security forum on Saturday in Singapore.

Pompeo said before the brief encounter during a group photo session at the Association of Southeast Asia Nations (ASEAN) regional forum that he had not held talks with Ri during his visit to Singapore.

Pompeo, who has been leading the U.S. negotiating in efforts to get North Korea to denuclearise, said earlier the process of ending the North's nuclear programme would take time but that he was optimistic that it would happen.