SEOUL, May 9--The Democratic People's Republic of Korea (DPRK) on Saturday test-fired three ballistic missiles into its eastern waters, Yonhap news agency quoted the South Korean military as saying.

The DPRK launched what were believed to be short-range KN-01 missiles in the sea off Wonsan, a major port on the North's east coast, between 4:25 p.m. and 5:23 p.m. local time, according to an official with the Joint Chiefs of Staff (JCS) in Seoul.

The test fire came after DPRK on Friday warned Seoul of " strikes without any prior warning" targeting South Korean naval ships if they continue to intrude into waters of the DPRK.

The command of the Korean People's Army (KPA) in the southwestern front issued a special warning, carried by the official news agency KCNA, accusing South Korea of sending 17 naval boats over the past seven days into the DPRK's territorial waters.

The DPRK on Saturday also has successfully test-fired a strategic ballistic missile from an underwater submarine, according to the KCNA.