The South Korean Embassy in Bangkok says it has received letters threatening to stage terrorist attacks against Seoul before the end of this month.

An embassy official said Wednesday that a group calling itself "the Yellow-Red Overseas Organization" had sent the letter, in which it threatened to launch attacks against major facilities in eight countries that have deployed troops to Iraq, including South Korea, Japan, Thailand and the Philippines.

Local police and intelligence officials are investigating the case and the embassy has asked police authorities to step up security measures.

The South Korean Embassy in Bangkok received a similar letter in January from a group calling itself the Anti-Korean Interests Agency, which vowed to attack Korean companies and facilities in Southeast Asian countries.