North Korea is trying to launch a biochemical attack against the South prior to the G20 Summit in Seoul in November, a conservative activist claimed Thursday citing a North Korean source.

Choi Sung-yong, the head of Family Assembly Abducted to North Korea said the North is preparing to send 20 different deadly biochemical weapons attached to balloons and parachutes across the border. He said the campaign is led by Gen. Kim Kyok-sik, who commands the North's frontline fourth corps, at the orders of leader Kim Jong-il's heir apparent Jong-un.

Choi said the story came from "an active soldier in the North Korean Army." Kim Kyok-sik was chief of the General Staff of the People's Army before being demoted to his current post and is thought to have masterminded the torpedo attack on the South Korean Navy corvette Cheonan.

Choi also claimed a number of North Korean mines found south of the border after recent floods were deliberately floated down the Imjin River by Kim Kyok-sik's men at Kim Jong-un's orders.

"The source said the frontline fourth corps is collecting mines from all over North Korea, not only in Hwanghae Province where the fourth corps is located but from as far a field as North Hamgyong Province. It floated the mines down intentionally but blamed it on floods," Choi claimed.

Asked about the claim, a National Intelligence Service spokesman was noncommittal, saying, "It's possible to imagine a number of scenarios, but we can't draw any conclusions at the moment." The Joint Chiefs of Staff declined to comment.