North Korea on Thursday tried and failed in what appeared to be its second attempt in two weeks to test a powerful, new medium-range ballistic missile, South Korea’s defence ministry said.

North Korea on Thursday tried and failed in what appeared to be its second attempt in two weeks to test a powerful, new medium-range ballistic missile, South Korea's defence ministry said.

A ministry official said the North had fired what was understood to be a Musudan missile at around 6:40 am (2140 GMT Wednesday) from Wonsan on the east coast, but it plunged back to earth seconds after launch.

"It is believed to have failed," the official told AFP.

There had been widespread intelligence reports in recent days that the North was preparing for another flight test of a Musudan, which is capable of striking US bases on the Pacific island of Guam.

North Korea initially launched a Musudan on April 15 -- the birthday of founding leader Kim Il-Sung -- but the exercise ended in what the Pentagon described as "fiery, catastrophic" failure, with the missile apparently exploding just after take-off.

The failed tests come as the country is gearing up for a rare and much-hyped ruling party congress next month, at which Kim Jong-Un is expected to take credit for pushing the country's nuclear weapons program to new heights.