Acting President Goh Kun has sent a letter of condolence to Russian President Vladimir Putin over the bomb blast that killed Chechen President Akhmad Kadyrov and twenty others on Sunday.

In the message, Goh expressed his deep condolences to those who were killed in the blast and the bereaved family members and hoped for the quick recovery of those who were injured.

Goh stressed that terrorism is a serious crime that cannot be justified by any means and vowed Seoul's active participation in the international community's fight to stamp out terrorism.

President Kadyrov was killed after a bomb ripped through a stadium in the Chechen capital during a Victory Day ceremony Sunday.

No group claimed responsibility for the explosion, which killed as many as 24 people. But the Associated Press said initial suspicion fell on separatist rebels, who have made Kadyrov a top target and attempted to assassinate him several times.