Seoul: North Korea has fired two unidentified projectiles into the sea off its eastern coast, South Korea's military says.

South Koreans watch a TV showing a report of a North Korea missile launch. Credit:AP

The latest launch on Saturday comes after US President Donald Trump said he received a "very beautiful letter" from North Korean leader Kim Jong-un.

North Korea has fired a series of missiles and rockets since Kim and Trump agreed at a June 30 meeting to revive stalled denuclearisation talks.

A US official said that at least one projectile was launched and that it appeared to be similar to previous short-range missiles fired by Pyongyang.