SEOUL (AFP) - A South Korean probe into a major cyber attack on its banks and broadcasters last month has determined North Korea's military intelligence agency was responsible, a report said on Wednesday.

The official investigation into access records and the malicious codes used in the attack pointed to the North's military Reconnaissance General Bureau as the source, Yonhap quoted a senior government official as saying.

The Ministry of Information declined to comment but has scheduled a press briefing for 2pm local time (1pm Singapore time).

The attack completely shut down the networks of TV broadcasters KBS, MBC and YTN, and halted financial services and crippled operations at three banks - Shinhan, NongHyup and Jeju.

The attack employed malware that can wipe the contents of a computer's hard disk as well as drives connected to the infected computer.

It came days after North Korea accused South Korea and the United States of being behind a "persistent and intensive" hacking assault that took a number of its official websites offline for nearly two days.

It also coincided with heightened military tensions on the Korean peninsula, following Pyongyang's nuclear test in February.