North Korea has staged thousands of cyber attacks against the South in recent years, causing financial losses of around $805 million, a Seoul lawmaker said Tuesday citing government data.

"A lot of data related to our national infrastructure, including chemical storage facilities and information relating to personal financial dealings have been stolen," ruling party MP Chung Hee-Soo said.

Using information provided by the Defense Ministry's cyber warfare unit, Chung told parliament that the South Korean military alone had been the target of 6,392 North Korean cyber attacks of varying scale since 2010.

The included website intrusions, malware deployments and the use of virus-carrying e-mails.

"Our military's cyber warfare ability to fend off such attacks...is incomparable to the North's, which is known to be one of the world's best," Chung said.

North Korea is believed to run an elite cyber war unit of 3,000 personnel, while the South has only 400 specialised staff.

As well as military institutions, recent high-profile cyber attacks have targeted commercial banks, government agencies, TV broadcasters and media websites.

The resulting financial damage since 2009 amounts to some 860 billion won ($805 million), Chung said.

North Korea has denied any involvement and accused Seoul of fabricating the incidents to fan cross-border tension.