North Korean leader Kim Jong Un once again supervised a "new weapon" launch, state media said Saturday, complicating efforts at denuclearisation ahead of next week's visit to Seoul by the US envoy to Pyongyang. 

North Korea fired what appeared to be two short-range missiles into the sea on Friday and launched a scathing attack on "foolish" calls for dialogue from South Korean President Moon Jae-in, rejecting further peace talks with Seoul.

North Korea threatened Tuesday to carry out more weapons tests after it fired its fourth pair of projectiles in less than two weeks following the start of joint exercises between the US and the South.

The rising temperature on the peninsula threatens to derail putative negotiations between Pyongyang and Washington, with the North saying the combined drills were a "flagrant violation" of the process.

Pyongyang fired two ballistic missiles on Wednesday, Seoul said, days after a similar launch that the nuclear-armed North described as a warning to the South over planned joint military drills with the United States.

A day after two North Korean missile launches rattled Asia, the nation announced Friday that it had tested a "new-type tactical guided weapon" that was meant to be a "solemn warning" about South Korean weapons development and its rival's plans to hold military exercises.

The message in the country's state media quoted North Korean leader Kim Jong Un and was directed at "South Korean military warmongers." It comes as U.S. and North Korean officials struggle to set up talks after a recent meeting on the Korean border between Kim and U.S. President Donald Trump seemed to provide a step forward in stalled nuclear negotiations.

North Korea lauded its ties with historic ally China on Friday as Xi Jinping wrapped up a highly symbolic two-day visit to his nuclear-armed neighbour, with both countries facing deadlock in their negotiations with US President Donald Trump.

Russia and China on Tuesday blocked an American initiative that aimed to halt fuel deliveries to North Korea, which Washington accuses of exceeding its annual ceiling for 2019, diplomatic sources said.

Moscow and Beijing said more time was needed to study the US request, which was backed by 25 UN members including Japan, France and Germany, according to the sources. 

The United States is accusing North Korea of breaching a UN-imposed ceiling on fuel imports by carrying out dozens of ship-to-ship transfers this year, according to a report obtained by AFP on Wednesday.

Backed by 25 countries including Japan, France and Germany, the United States asked a UN sanctions committee to rule that the annual cap of 500,000 barrels had been exceeded and order all countries to immediately halt fuel deliveries to North Korea.

Kim Jong Nam, the estranged half brother of North Korean leader Kim Jong Un who was killed in Malaysia in 2017, was a CIA informant, the Wall Street Journal reported Tuesday.

North Korea is experiencing its worst drought in over a century, official media reported Friday, days after the World Food Programme expressed "very serious concerns" about the situation in the country.