North Korea has fired an unidentified projectile, South Korea's military said, a week after its latest missile launch.

South Korea's Office of Joint Chiefs of Staff said in a statement that the projectile took off on Sunday afternoon from a location near Pukchang.

The missile flew about 500 kilometres and was believed to have landed in waters off its east coast, South Korea's military said.

The Office of Joint Chiefs of Staff said South Korea and the United States were conducting close-up analysis of the launch.

"Our military is closely monitoring the North Korean military for any further provocation and maintaining readiness to respond," South Korea's Joint Chiefs of Staff said in a statement.

Last week Pyongyang launched an intermediate-range missile named the Hwasong-12, its longest-range missile yet, according to analysts.

READ MORE: North Korea's nuclear weapons - all we know

It was its 10th launch this year, after dozens in 2016, as it accelerates efforts to develop an intercontinental ballistic missile (ICBM) capable of delivering a nuclear warhead to the continental United States - something US President Donald Trump has vowed "won't happen".

Pyongyang has long had missiles that can reach targets across the South and Japan.

Such tests present a difficult challenge to new South Korean President Moon Jae-in, a liberal who took office on May 10 and has expressed a desire to reach out to North Korea.

North Korea's latest launch came hours after Moon named his new foreign minister nominee and top advisers for security and foreign policy.