North Korean hackers have allegedly stolen large cache of military documents from South Korea including a plan to assassinate their North’s leader Kim Jong-un.

The compromised documents include wartime contingency plans drawn up by the US and South Korea and also include reports to the allies’ senior commanders, Rhee Cheol-hee, a South Korean lawmaker was quoted as saying BBC Tuesday.

The South Korean defence ministry has so far refused to comment about the allegation.

Plans for the South's Special Forces were reportedly accessed, along with information on significant power plants and military facilities in the South.

Mr Rhee belongs to South Korea's ruling party, and sits on its parliament's defence committee. He said some 235 gigabytes of military documents had been stolen from the Defence Integrated Data Centre, and that 80% of them have yet to be identified.

The hack took place in September last year. In May, South Korea said a large amount of data had been stolen and that North Korea may have instigated the cyber-attack - but gave no details of what was taken.

North Korea denied the claim.