South Korea said Friday that it is closely monitoring North Korea's missile development in cooperation with the United States amid a news report that the North has conducted another rocket engine test.

North Korea has conducted the test of a rocket engine that could be seen as part of the North's program to develop an intercontinental ballistic missile, Reuters reported, citing a US official.

South Korea's unification ministry said that the South's military believes that North Korea is continuing activities aimed at advancing its missile capability.

"South Korea is closely monitoring the situation under the collaboration with the US," said Lee Eugene, vice ministry spokesperson at a regular press briefing.

North Korea's state media has not released a relevant report.

If confirmed, the North's move marked the first time since March that it carried out a ground test of a new high-thrust rocket engine.

North Korea is developing nuclear weapons and missiles at an alarming pace with its stated goal of launching an ICBM capable of hitting the US mainland. (Yonhap)