Investigators conduct an on-site investigation at the scene of the Jeju Air crash at Muan International Airport in Muan, Jan. 3. Yonhap

Police said Monday they will conduct an international joint investigation over a Japanese email claiming responsibility for last week's fatal Jeju Air crash at Muan International Airport.

Police began the investigation a week ago after a Ministry of Justice official received the email sent by a person claiming to be a Japanese lawyer, following the Dec. 29 plane crash that killed 179 people. The email also contained threats to detonate high-powered bombs in several downtown areas of Korea.

"We plan to request cooperation from the Japanese police through Interpol and pursue international criminal justice cooperation through diplomatic channels," an official at the Korean National Police Agency (KNPA) said.

Police suspect the latest email threat may have been committed by the same perpetrator who had sent similar emails and faxes to major domestic organizations since August 2003.

Meanwhile, the KNPA said it was investigating 126 malicious online comments about the Jeju Air crash victims and their bereaved families as of 5 p.m. Sunday. (Yonhap)