North Korea has fired two ballistic missiles off its east coast as Kim Jong Un's sister warned of "using the Pacific as our firing range".

The missiles were launched on Monday morning local time and fell into the sea outside Japan's exclusive economic zone, the country's coast guard said.

There were no reports of damage to aircraft or vessels.

Japan's defence ministry said the missile launches "threaten the peace and security of Japan, the region, and the international community".

North Korea's state media KCNA confirmed it had fired two projectiles, aiming at targets 245 miles and 209 miles away.

It said the "multiple rocket launcher mobilised in the firing... is a means of tactical nuclear weapon" capable of "paralysing" an enemy airfield.

The incident comes just two days after North Korea fired an intercontinental ballistic missile into the sea off Japan's west coast, in what state media described as a move to strengthen its "fatal" nuclear attack capacity.

In response to Saturday's launch, the US and South Korea held joint air exercises on Sunday.

Those exercises prompted a warning from Kim Yo Jong, sister of North Korea's leader Kim Jong Un.

She said that South Korea and the US were "openly showing their dangerous greed" and were making an "attempt to gain the military upper hand and predominant position in the Korean Peninsula".

She added: "I warn that we will watch every movement of the enemy and take corresponding and very powerful and overwhelming counteraction against its every move hostile to us.

"There is no change in our will to make the worst maniacs escalating the tensions pay the price for their action.

"We are carefully examining the influence (the military drills) would exert on the security of our state.

"The frequency of using the Pacific as our firing range depends upon the US forces' action character."

North Korea says the military drills are a rehearsal for invasion but South Korea and its allies say they are defensive.