North Korea has reportedly refloated a warship about two weeks after it capsized during a launch attempt, in an incident that drew harsh criticism from the country's leader Kim Jong Un. State-run news agency KCNA reported on Friday that the warship had "safely entered the water vertically" and had then been "moored at the pier".

Satellite images and videos show how launching a 5,000-ton warship into the water sideways can cause it to capsize if done incorrectly.

North Korea has arrested four people it claims bear responsibility for a launch accident last week that left leader Kim Jong Un’s newest warship lying on its side and partially submerged in a shipyard,