SEOUL, March 16 (Reuters) - North Korea fired an "unknown projectile" on Wednesday which appeared to fail immediately after launch, South Korea's military said after Japanese media reported a suspected missile launch by the nuclear-armed North.

The launch comes after the United States and South Korea warned that North Korea may be preparing to test-fire an intercontinental ballistic missile (ICBM) at full range for the first time since 2017.

The projectile was fired from an airfield outside the North Korean capital of Pyongyang, South Korea's Joint Chiefs of Staff (JCS) said in a statement.

"It is presumed that it failed immediately after launch," the statement said.

A source at Japan's Ministry of Defence called the projectile a potential ballistic missile, Japanese public broadcaster NHK reported.

The airfield has been the site of several recent launches, including on Feb. 27 and March 5. North Korea said those tests were for developing components of a reconnaissance satellite and did not identify what rocket it used, but Seoul and Washington said they were tests of a new ICBM system.

Reclusive North Korea has fired missiles at an unprecedented frequency this year, conducting its ninth weapons test on March 5, drawing condemnation from the United States, South Korea and Japan.

The USS Abraham Lincoln aircraft carrier led military exercises in the Yellow Sea, and air defence artillery at Osan air base in South Korea intensified drills in response to the increased North Korean missile activity, U.S. forces in Asia said on Tuesday.

The new ICBM system, the Hwasong-17, was unveiled at a military parade in 2020 and reappeared at a defence exhibition in October 2021.

The Feb. 27 and March 5 launches did not demonstrate the missile's full range, and analysts said the North might have used only one stage of the missile or adjusted its fuel volume to fly at lower altitudes.

The Hwasong-17 would be North Korea's largest ICBM yet, and the government appears to be restoring some tunnels at its shuttered nuclear test site, U.S. and South Korean officials said last week.

North Korea has not tested an ICBM or nuclear bomb since 2017, but has said that it could resume such testing because denuclearisation talks with the United States are stalled.