North Korean leader Kim Jong Un has said an elevated U.S. security partnership with South Korea and Japan poses a grave threat to his country and vowed to further bolster his nuclear weapons program.

North Korea reacted to US President Donald Trump's recent meeting with Japan's prime minister by insisting its nuclear program is not up for negotiation.

Egypt will host an emergency Arab summit on 27 February to discuss what it described as "serious" developments for Palestinians, according to a statement from the Egyptian foreign ministry on Sunday.