North Korea has fired two short-range projectiles into waters off its east coast, a day after South Korea rejected its proposals to reduce tensions, including the cancellation of annual drills between Seoul and Washington.

The projectiles, with a range of 180 kilometres (110 miles), were fired from the eastern coastal city of Wonsan and harmlessly landed in the sea on Wednesday morning, South Korean defence officials said requesting anonymity citing department rules.

The officials gave no further details.

The launches came a day before Chinese President Xi Jinping visits South Korea for a summit meeting with his South Korean counterpart Park Geun-hye.

The firings were the third such reported launches since Thursday.

South Korean officials said the North fired three short-range projectiles on Thursday and two short-range missiles on Sunday, both into waters off the east coast.

The North's state media later said leader Kim Jong Un inspected test launches of missile and rockets in a likely reference to the launches.

On Monday, North Korea's powerful National Defence Commission made a set of proposals it said would ease tension, calling for the cancellation of the drills because they are a rehearsal for invasion.

It also suggested that the two Koreas halt hostile military acts against each other at border areas and stop psychological warfare.

South Korea and the US have repeatedly denied that they seek to invade the North.

South Korea on Tuesday dismissed as insincere the North Korean proposals, saying the North must first demonstrate that it is serious about nuclear disarmament if it truly wants peace.

Animosity on the Korean Peninsula remains high following a slew of missile and rocket tests by North Korea. The two Koreas also earlier exchanged artillery fire along a disputed western sea boundary.

The Korean Peninsula officially remains in a state of war because the 1950-53 Korean War ended with an armistice, not a peace treaty.