France on Wednesday banned two citizens' rallies planned for a crunch climate conference due to open in Paris just two weeks after terror attacks killed 129 people in the French capital.
Climate activists reacted with a mix of disappointment and understanding and vowed to find alternative ways to make their voice heard at the summit tasked with delivering a climate rescue pact.
Rallies to beat the drum for concerted political action against global warming had been planned for November 29, the day before some 120 heads of state and government are meant to open the summit, and December 12, the day after it closes.
"The situation created by the odious attacks of November 13, and the investigations under way since then, require that security conditions be reinforced," French Foreign Minister Laurent Fabius, who will preside over the summit, said in a statement.
"To avoid any additional risk, the government has decided not to authorise climate marches in public places in Paris and in other French cities on November 29 and December 12."
Green groups urged people around the world to join the other 2,173 events being planned worldwide as part of a Global Climate March on November 28 and 29.
"Now it's even more important for people everywhere to march on the weekend of November 29th on behalf of those who can't, and show that we are more determined than ever to meet the challenges facing humanity with hope, not fear," said Emma Ruby-Sachs of campaign group Avaaz.
"The government can prohibit these demonstrations, but it cannot stop the mobilisation and it won't prevent us strengthening the climate movement," added Nicolas Haeringer of 350.org.
Fabius said the decision had been "difficult" and was sure to disappoint many, "but in the current context, security requirements take priority."
Other climate gatherings in spaces that are "enclosed and easily secured" will go ahead, he added.
The French government has said it will not "give in" to terrorism and insists the long anticipated conference will go ahead.
The stakes are high: 195-nations gathered under the UN climate forum have set themselves the task of inking a pact to curb greenhouse gas emissions blamed for dangerous levels of climate change.
About 40,000 delegates, journalists, observers, NGOs and other participants are accredited for the November 30-December 11 marathon negotiation.
A security source told AFP that 5,000-odd police and military police would be needed to secure the November 29 rally, and that too in the midst of a national state of emergency and massive anti-terror deployment