South Korea investigates computer 'attack'

South Korean officials are investigating a suspected cyber-attack that has paralysed computer networks at broadcasters and banks.

Broadcasters KBS, MBC and YTN told police their networks were halted around 14:00, Yonhap news agency reported.

Two banks, Shinhan Bank and Nonghyup, said their networks were affected.

The cause of the problems remains unknown. Last week, North Korea accused the US and its allies of attacks on its internet servers.

Tension has been high on the Korean peninsula in recent weeks, following Pyongyang's 12 February nuclear test.

"Members of our cyber team are investigating this now," a National Police Agency spokesman was reported as saying AFP news agency.

Staff at the three broadcasters said their computers crashed and could not be restarted, with screens simply displaying an error message, the BBC reports.

South Korean internet service provider LG Uplus told Reuters news agency it believed its network had been hacked.

An official from the presidential office told Yonhap the authorities were "now trying to determine the cause of the network paralysis", adding it was not yet known whether North Korea was involved.

No government-related computer networks had been affected, an official from the National Computing and Information Agency (NCIA) told the agency.

The military has upgraded its information surveillance status by one level, Yonhap said.

North Korea is believed to have been behind two major cyber-attacks on the South, in 2009 and 2011, that targeted government agencies and financial firms.

It has stepped up rhetoric in recent days in response to fresh UN sanctions over its nuclear test and joint annual military drills between the US and South Korea, which it bitterly opposes.