A total of 138 heads of state and government so far will attend a climate summit due to kick off in terror-hit Paris on November 30, the French government said Friday.

Panama's President Juan Carlos Varela was the latest to confirm he will be present for the opening by world leaders including US President Barack Obama, China's Xi Jinping, Narendra Modi of India and Russia's Vladimir Putin, a French presidency official said.

The summit will open in the French capital just two weeks after a coordinated jihadist massacre of 130 people out for dinner, drinks and a concert on a Friday night.

France has said it will not "give up in the face of violence" by cancelling the summit tasked with producing the first-ever deal committing all the world's nations to climate action starting in 2020.

The presidency said no head of state or government had cancelled attendance since last Friday's onslaught by gunmen and suicide bombers.

And French President Francois Hollande, it said, would remain "completely involved" in the conference despite a packed schedule at home and abroad in the wake of the violence.

The conference itself will gather some 40,000 delegates, journalists, observers and exhibitors.

Citing security concerns, the French government has cancelled two mass rallies -- one planned for the eve of the marathon meeting, and the other after its close.

The overarching goal of the climate talks is to limit average global warming to two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels.

This is the threshold beyond which scientists warns our host planet will become increasingly inhospitable -- racked by superstorms, drought and land-gobbling sea level rise.

About 170 countries have already filed voluntary carbon-curbing pledges to underpin the future pact, but scientists say the aggregate effect falls far short and Earth is on course for warming of about 3 C, or more.

But negotiators remain deeply divided, with rich and developing nations arguing about who must do what to curb carbon emissions, and who must pay.

Despite attacks, world leaders ready to talk climate in Paris: UN envoy
United Nations, United States (AFP) Nov 20, 2015 - The Paris attacks are affecting preparations for the climate change conference in the French capital, but leaders are still focussed on clinching a deal, a UN envoy said Friday.

"World leaders, one after the other, are reconfirming that they are going to Paris because they think this is an important event," said Janos Pasztor, the UN Assistant Secretary-General on climate change.

US President Barack Obama, China's Xi Jingping and Russian President Vladimir Putin are among the 138 leaders who will attend the climate summit in Paris starting November 30.

Security has been beefed up following the terrorist attacks on November 13 that left 130 dead and hundreds wounded, and a major march has been cancelled.

"The attacks in Paris are affecting the preparations and activities planned for COP21," Pasztor told a news conference.

The UN official downplayed suggestions that leaders may switch the conversation from combating catastrophic global warming to battling terrorism during their Paris meetings.

"It's inevitable that when leaders meet, they talk about all the issues that are important," he said.

But he added that they are "putting their travel plans where their mouths are", meaning that their presence in Paris should be seen as proof of how seriously they take the climate issue.

The summit will open in Paris just two weeks after coordinated attacks on a concert hall, football stadium, bars and restaurants that were claimed by the Islamic State group.

While a major march planned for November 29 has been scrapped, there will be more than 2,000 rallies in cities worldwide to press demands for action from the leaders in Paris, said the envoy.

The goal of the climate talks is to strike a deal to limit average global warming to two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels.

"The climate change conference in Paris is not the end point," said Pasztor.

"It must mark the floor, not the ceiling of our ambition. It must be the turning point toward a low-emission climate-resilient future."

The envoy said he was optimistic that a deal could be reached, but cautioned that a great deal of work lay ahead to reach a "universal, meaningful agreement."