The Defence Ministry official, who spoke on condition of anonymity, citing department rules, said the missiles were fired from Wonsan in Gangwon Province and are presumed to be short-range ballistic missiles.
The official said North Korea fired the missiles without designating no-sail zones, which the South Korean military views as a clear provocation. South Korean media quoted officials as saying the projectiles appeared to be Scud missiles.
As it unleashed a torrent of rhetoric in state media condemning annual U.S.-South Korean military drills earlier this year, Pyongyang also conducted series of missile and artillery tests that boosted tensions with rival Seoul. The North says it considers its rivals' annual springtime drills as preparation for an invasion.
The country said Friday that leader Kim Jong Un guided test launches of a newly developed precision-guided missiles, in a likely reference to three short-range projectiles South Korean officials say the North fired a day earlier.
Still, the impoverished North devotes much of its scarce resources to its missile and nuclear programs, which subsequently pose a serious threat to South Korea, Japan and tens of thousands of U.S. Troops in the region. Outside analysts say North Korea has developed a handful of crude nuclear devices and is working toward building a warhead small enough to mount on a long-range missile, although most experts say that goal may take years to achieve.