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.
A day earlier, police had detained nearly 1,000 activists at the tail end of a 40,000-strong march toward the suburban conference center where the 192-nation U.N. climate conference is being held.
The detainees were from a range of European countries as well as the U.S, Kenya, Belarus, Japan, Mongolia, China and Turkey, police said.
Only 13 of them remained in custody Sunday. Of those, three — two Danes and a Frenchman — were set to be arraigned in court on preliminary charges of fighting with police.
Police said they detained the activists when some of them started breaking windows of buildings in downtown Copenhagen. A police officer received minor injuries when he was hit by a rock thrown from the group and one protester was injured by fireworks, Steen Munch said.
Critics blasted the Danish law that allows police to make preventative arrests if they believe a demonstration will turn violent and hold suspected troublemakers for up to 12 hours without a court arraignment.
"They have arrested 1,000 people. And they only followed up on three of them," Amnesty spokeswoman Ida Thuesen said. "There are lot of people who haven't done anything and had no intention of doing anything."
The conference took a day off Sunday, though more than 40 environment ministers and other high-level negotiators were meeting for informal talks at the Danish Foreign Ministry on greenhouse emissions cuts and financing for poor nations to deal with climate change.
The pledges on emissions cuts so far are short of the minimum proposed in a draft agreement to keep temperatures from rising to a dangerous level.
Also Sunday, Christian leaders from around the world took part in an ecumenical service dedicated to climate change and led by Archbishop of Canterbury Rowan Williams at Copenhagen's Lutheran cathedral.
Archbishop Desmond Tutu of South Africa joined church leaders from Tuvalu, Zambia, Mexico, Greenland and Denmark to warn about the dangers of a warming world.
They carried symbols of climate change, a glacier stone from Greenland and bleached corals from the Pacific Ocean. The Rev. Suzanne Matale of Zambia held up a dried-up cob of corn.
"Many people have already perished as a result of droughts, floods and desertification brought about by climate change," Matale said.
After the service the church bells sounded 350 times in a campaign to draw attention to global warming. The National Council of Churches in Denmark says Christian churches in Denmark and across the globe were part of the campaign, from Fiji in the South Pacific to the U.S. and Canada.
About 300 churches in Sweden took part, including the Cathedral in Stockholm's Old Town.
Many scientists say 350 parts per million is the upper level of what is considered a safe concentration of CO2 in the atmosphere.
The European Union, Japan and Australia joined the U.S. Saturday in criticizing the draft global warming pact that says major developing nations must rein in greenhouse gases, but only if they have outside financing. Rich nations want to require developing nations to limit emissions, with or without financial help.
Indian Environment Minister Jairam Ramesh said his country — the world's No. 5 greenhouse gas polluter — will not offer more than its current pledge to slow its growth rate of emissions. It has offered to cut greenhouse gases measured against production by 20 to 25 percent by 2020.
China has made voluntary commitments to rein in its carbon emissions but doesn't want to be bound by international law to do so.