South Korea said Tuesday it will step up IT security within the government to fend off cyber attacks from North Korea, which it has accused of mounting a series of strikes in recent years.

Under a presidential decree, 45 officials at 23 government agencies will be appointed to take charge of computer security and emergency planning, the home affairs ministry said.

"This measure is aimed at helping fend off cyber attacks that have been taking place continuously," a ministry official told AFP.

Earlier this month, South Korean prosecutors said North Korean military intelligence launched a cyber attack that paralyzed operations at one of the country's largest banks.

North Korea's defence ministry flatly denied the allegation as "absurd".

Seoul also accused Pyongyang of staging cyber attacks on websites of major South Korean government agencies and financial institutions in March this year and in July 2009.

Pyongyang also rejected those allegations, accusing Seoul inventing the charges to raise tensions.

The North reportedly maintains elite hacker units, prompting the South to set up a specific military command to combat them.

Tensions between the nations have been high since the South accused the North of sinking one of its warships in March last year near their disputed sea border in the Yellow Sea, killing 46 sailors.

Pyongyang denied the charge but went on to shell the South's Yeonpyeong island last November, killing four people including civilians.