North Korea 'has cyber warfare staff of 6,000 people'
South Korea says rival North Korea has a 6,000-member cyber army dedicated to disrupting the South's military and government.
The figure, in a report from Seoul's defence ministry, is a dramatic increase from South Korea's earlier estimate that the North had a cyber warfare staff of 3,000.
The report also said North Korea may now have the ability to strike the US mainland because of its recent progress in missile technology and is advancing in efforts to miniaturise nuclear warheads to mount on such missiles.
The United States has accused North Korea of a cyber attack on Sony Pictures over a film depicting the fictional assassination of the North's leader.
The Korean Peninsula is still in a technical state of war because the 1950-53 Korean War ended in an armistice, not a peace treaty.
North Korea has denied any involvement in the breach of tens of thousands of confidential Sony emails and business files.
Former South Korean defence minister Kim Kwan-jin said in 2013 that North Korea was operating a cyber warfare staff of 3,000.
South Korea has accused North Korea of conducting at least six high-profile cyber attacks since 2007 and many more unsuccessful attempts to infiltrate computer systems of businesses and government agencies.