North Korea test-fired its latest anti-aircraft missile system in a drill watched by leader Kim Jong-un, state media reported on Friday, as the nuclear-armed state lashed out at US-South Korea joint drills.

The launch proved the system's "combat fast response," the Korean Central News Agency said, and came a day after South Korea wrapped up a major annual joint military exercise with the United States, known as Freedom Shield.

Kim praised the latest anti-aircraft system, saying North Korea's army would be "equipped with another major defence weapon system with laudable combat performance," the news agency wrote.

It did not specify where the test took place.

Seoul said last week the North fired "multiple unidentified ballistic missiles" after it began the joint drills involving US soldiers stationed in South Korea.

In a separate statement on Thursday, an official for the North's defence ministry denounced the military exercise as "no more than a rehearsal of war of aggression."

Pyongyang also carried out a test-launch of strategic cruise missiles in the Yellow Sea in late February, which it said showed off "counterattack capabilities."

The most recent Freedom Shield exercise featured a collaborative drill focused on countering weapons of mass destruction, specifically targeting nuclear, chemical, biological, and radioactive threats.

Relations between Pyongyang and Seoul have been at one of their lowest points in years, with the North launching a flurry of ballistic missiles last year in violation of UN sanctions.

South Korean and Western intelligence agencies have said that more than 10,000 soldiers from the reclusive North were sent to Russia last year to help it fight a shock Ukrainian offensive into the Kursk border region.

Seoul's spy agency said last month that the North has sent more soldiers to Russia and re-deployed several to the frontline in Kursk.

A report by Seoul's defence ministry said the North was "continuing to provide weapons, ammunition and other military support to Russia following its troop deployment in the Ukraine war". (AFP)