The claim comes after Washington, Seoul and Tokyo began joint military exercises on Thursday.

North Korea has criticised a joint military exercise by the United States, South Korea and Japan, saying such drills show the relationship among the three countries has developed into “the Asian version of NATO”, state media reported.

“We strongly denounce… provocative military muscle-flexing against the DPRK [Democratic People’s Republic of Korea],” Pyongyang’s Ministry of Foreign Affairs said in a statement carried by the state-run KCNA news agency on Sunday.

“The US-Japan-ROK [South Korea] relations have taken on the full-fledged appearance of an Asian-version NATO,” it said, warning of “fatal consequences”.

“The DPRK will never overlook the moves of the US and its followers to strengthen the military bloc.”

On Thursday, the US, Japan and South Korea began large-scale joint military drills called “Freedom Edge” involving navy destroyers, fighter jets and the nuclear-powered US aircraft carrier Theodore Roosevelt, aimed at boosting defences against missiles, submarines and air attacks.

The exercise was devised at a three-way summit at Camp David in the US last year to strengthen military cooperation amid tensions on the Korean Peninsula stemming from North Korea’s weapons testing.

North Korea has long condemned joint drills between the United States and South Korea as a rehearsal for invasion and proof of hostile policies by Washington and Seoul.

On Sunday, South Korea rejected North Korea’s accusations and said that the latest exercises are a continuation of defensive drills held regularly for years among the three allies.

“It is absurd that North Korea, the primary source of tension on the Korean peninsula, criticises the Freedom Edge exercise by labelling it as an ‘Asian NATO’,” the South Korean Ministry of National Defense said in a statement.

Seoul has also said it will review the possibility of supplying arms directly to Ukraine, in protest against a recent mutual defence pact signed between North Korean leader Kim Jong Un and Russian President Vladimir Putin.

South Korea and the US have also accused the North of supplying weapons to Russia that are being used in its war in Ukraine.

Both Russia and North Korea have denied any such transactions.