Police say a South Korean woman tried to set herself on fire near the Seoul convention center where the Group of 20 leaders' summit will take place.
Police say the woman doused herself with paint thinner and then shouted, "I oppose the G-20" as she tried to set herself on fire on Thursday morning.
Security guards stopped her and say she wasn't hurt. She was taken in for questioning.
Seoul authorities are on high alert as the summit gets under way later on Thursday with more than 30 leaders from the world's major and emerging economies taking part.