BARCELONA: Climate change activists expressed disappointment at a decision by France to cancel street demonstrations around upcoming UN climate talks, after bloody attacks in Paris, but vowed their calls for a strong new deal to curb global warming would still be heard.

On Wednesday evening, the French government said security concerns meant it could not allow a huge march to take place on November 29, the day before the talks start, or other actions planned for December 12, at the end of the two-week negotiations.

The decision follows attacks by militant Islamists last Friday in Paris that killed 129 people.

The government also ruled out climate marches in public places in other French cities, but said planned civil society activities could go ahead in closed spaces or where security could be ensured.

Alix Mazounie, international policy coordinator for RAC France, a coalition of 16 associations working on climate change, said organisers were concerned for people's safety and had pushed hard to find an alternative way of holding the marches - for example, inside a stadium.

But the French government "gave up on us very quickly", she said, despite continuing to permit tourists to visit the Eiffel Tower and outdoor Christmas markets.

"It's basically saying we don't think your voices are that important that we should make sure they can be expressed somehow," she told the Thomson Reuters Foundation by phone.

Nonetheless, 57 marches calling for climate justice will be held in other cities around the world the weekend before the Paris conference starts, she noted.

These may now attract bigger crowds, she said. "People will want to stand in solidarity with us and march on our behalf, represent us and our voices," she said.

Climate change activists in Paris are meeting today and tomorrow to decide on alternative, creative ways to mobilise instead of marching, including online and artistic means.

Jean François Julliard, executive director of Greenpeace France, said "huge numbers" of marchers had been expected in Paris and "those people will not be silenced".

"We will find new, imaginative ways to ensure our voices are heard in the UN conference centre and beyond," he added in a statement.

The Coalition Climate 21 alliance said a Citizens Climate Summit should be able to proceed on December 5 and 6, as well as a "Climate Action Zone" in a northern Paris cultural centre, due to open for the second week of the talks as a venue for public workshops, meetings and other events.

French Foreign Minister Laurent Fabius acknowledged that the "difficult decision" to cancel the marches would disappoint some who had planned to participate.

But he said in a statement that the UN conference, known as COP21, would continue to welcome civil society organisations, which "play a major role".

RAC France's Mazounie said she did not think citizen pressure for an ambitious agreement to tackle climate change would be diminished as a result of the Paris march decision.

"It's not just a Paris message, it's coming from everywhere," she said.

Nicolas Haeringer, France campaigner for climate activism group 350.org, noted that "the movement for climate justice will not slow down".

"Together, we will continue to stand against violence and hatred with our peace and resolve," he said in a statement.

HEAT ON LEADERS

Mazounie said the attacks in Paris should give around 130 world leaders due to attend the first day of the talks the incentive to push for a stronger deal that will limit planet-warming emissions beyond current plans.

"Hopefully leaders in Paris will feel the heat and understand that if you want to combat terrorism, you also need to tackle climate change," she said.

Climate change impacts - including more extreme weather and rising seas - are causing social instability, hunger and displacement around the world, she added.

Andrew Steer, president of the World Resources Institute, said it would be difficult for visiting leaders to express their solidarity with France after the Paris attacks and then say they were not in the mood to seal a global climate change deal.

"If anything, it has stiffened the spine in terms of determination to really solve what is the greatest collective action problem in history," he told journalists.