South Korea on Thursday said it would double its cyber-security budget and train 5,000 experts amid growing concern over its vulnerability to attacks it blames on North Korea.

The government is to boost its budget to 10 trillion won ($8.76 billion) to be spent by 2017, the science ministry said. The training will take place over the same period.

North Korea was blamed for major intrusions in 2009 and 2011 that targeted South Korean financial institutions and government agencies.

In the most recent case, Seoul accused Pyongyang's military intelligence agency of launching a major cyber attack on South Korean banks and broadcasters in March.

North Korea is believed to have a cyber warfare unit staffed by around 3,000 people. In response, the South set up a special cyber command unit in early 2010 but there is no official figure on the number of experts who work there.