North Korea has rejected any further talks with South Korea, calling its decision “completely the fault of South Korea’s actions”.
It issued a statement in response to a speech by South Korea President Moon Jae-in on Thursday.
Meanwhile, early on Friday North Korea test-fired two missiles into the sea off its eastern coast, the South Korean military said.
It is the sixth such test in less than a month.
The two “unidentified projectiles” were fired about 08:00 (23:00 GMT Thursday) and travelled 230km (140 miles) reaching an altitude of 30km (18 miles), South Korea’s Joint Chiefs of Staff said.
Six days ago, North Korea fired two short-range ballistic missiles into the Sea of Japan/East Sea.
The series of tests comes after US President Donald Trump and North Korean leader Kim Jong-un agreed during a meeting in June to restart denuclearisation negotiations.
North Korea has faced international sanctions for its development of nuclear weapons.
In a speech marking Korea’s liberation from Japanese rule, President Moon vowed to unite the Korean peninsula by 2045.
Korea divided into two countries at the end of World War Two.
President Moon said the goal of achieving denuclearisation on the Korean peninsula was at its “most critical juncture”, as talks between North and South appear deadlocked.