North Korea on Sunday fired four suspected shots from its multiple rocket launchers into the Yellow Sea, South Korean military officials said, the latest show of force that could heighten tensions on the Korean Peninsula.

South Korea's National Security Council (NSC) held an emergency vice-ministerial meeting over the four shots that fell into the western waters during a span of an hour from 7:20 a.m. from an unspecified location in South Pyongan Province, according to officials.

Park Kyung-mee, presidential office spokesperson, said the NSC meeting members stressed the need to maintain "a firm defense readiness posture" based on the South Korean military's enhanced capability and the South Korea-US alliance during a time of a government power transfer.

"There were shots believed to be that of North Korea's multiple rocket launchers this morning," an official of the South Korean military said.

"We are maintaining our defense readiness posture while closely following related developments," the official added.

The multiple rocket launcher firings came amid tensions on the Korean Peninsula over North Korea's tests of an intercontinental ballistic missile system on Feb. 27 and March 5.

North Korea also launched an apparent ballistic missile on Wednesday, but the missile appears to have exploded in midair at an altitude of below 20 kilometers, according to South Korea. (Yonhap)