Danish police outnumbered protesters on Sunday, detaining more than 200 people on a second day of demonstrations as environment ministers met for informal talks to advance negotiations on a new pact.
Meanwhile, church bells in Denmark and other countries rang 350 times, a number that refers to what many scientists consider a safe level of carbon dioxide in the air.
Police stopped an unauthorized demonstration headed toward the city's harbor and carried out a security check of some of the participants, Copenhagen police spokesman Flemming Steen Munch told The Associated Press.
The hundreds of demonstrators were outnumbered by police officers in riot gear who surrounded them. Steen Munch said police found bolt-cutters and gas masks when they searched a truck that led the demonstration. At least 200 activists were detained, he said.