North Korea launched a suspected ballistic missile that detonated mid-air shortly after launch, according to Seoul, with analysts warning that it was most likely a botched test of Pyongyang's so-called "monster missile".

The launch -- North Korea's tenth suspected weapons test this year -- comes after the United States claimed the nuclear-armed country was preparing to fire an intercontinental ballistic missile (ICBM) "at full range" for the first time since 2017.

Despite international sanctions, Pyongyang conducted seven missile tests in January and twice launched components of what it said was a "reconnaissance satellite".

Last week, South Korea and the United States announced that the tests were made of a new ICBM system that has never been fired before, most likely the Hwasong-17 referred to as the "monster missile". 

The suspected ballistic missile "seems to have exploded in midair shortly after launch," Seoul's Joint Chiefs of Staff told AFP.

The launch took place at about 09:30 am (1230 GMT) from the Sunan area of Pyongyang, the same location as the February 27 and March 5 satellite tests.

Nuclear-armed North Korea has long desired an intercontinental ballistic missile capable of carrying multiple warheads, and the US declared last week that the previous tests indicated a "significant escalation" of the country's nuclear programs.

However, according to the NK News site, the Wednesday launch ended in "catastrophic failure", with a red-tinged ball of smoke zigzagging across the sky as debris dropped near the city.

All this comes as the US military this week said it had enhanced missile defense systems in South Korea.

Monster missile 

North Korea has conducted three ICBM tests, the most recent of which was in November 2017 with a Hwasong-15 believed powerful enough to reach Washington and the whole of the continental United States.

However, since leader Kim Jong Un began on a flurry of high-level diplomacy in 2018, the country has been observing a self-imposed embargo on testing long-range and nuclear missiles.

Negotiations with the US President at the time, Donald Trump, broke down a year later, and Kim has since doubled down on his ambitions to modernize his military while disregarding US offers of negotiations.

"Signs indicate the North test-fired Hwasong-17 today," Cheong Seong-chang, a senior researcher at the private Sejong Institute told AFP.

Pyongyang would meticulously examine the failure of the Wednesday launch, and it may take three tests to guarantee the rocket is operational, he warned.

"I expect the North to conduct one or two more test launches before April 15," he said.

North Korea will commemorate the 110th anniversary of the birth of its founding leader and Kim's grandfather, Kim Il Sung, in April. Such anniversaries are usually accompanied by military parades or launches to exhibit the country's capabilities. 

"The Kim regime wants to demonstrate new technical achievements around the 110th birth anniversary of its founder, Kim Il-sung," said Leif-Eric Easley, a professor at Ewha University in Seoul.

"If the most recent missile launch was indeed a failure, North Korea will almost certainly continue to test," he added.

Satellite images indicate that North Korea is preparing for a military parade for the April anniversary.