US President Barack Obama has said he will press ahead with a visit to Paris for climate talks, calling on world leaders to make a similar show of resolve.

Speaking in Kuala Lumpar, Mr Obama said "I think it's absolutely vital for every country, every leader, to send a signal that the viciousness of a handful of killers does not stop the world from doing vital business."

Mr Obama's call comes as a French presidency source said a number of heads of state have confirmed they will attend the talks on 30 November, in spite of attacks by so-called Islamic State militants on 13 November that killed 130 people.

Speaking to Reuters, the source said no head of state has cancelled, adding that 138 world leaders are expected on the opening day of the UN Climate Change conference.

World leaders will discuss plans to curb greenhouse gas emissions and prevent global temperatures rising more than 2C above pre-industrial levels at the conference, which is to run until 11 December.

Some 40,000 to 45,000 people are expected to attend the event, also dubbed COP21, which will be held at Le Bourget, north of Paris, a conference management source said.

French Prime Minister Manuel Valls said on Monday that no foreign leaders had asked France to postpone the summit, a move he said would amount to "abdicating to the terrorists".  

All precautions taken to avoid chemical attack

French defence minister Jean-Yves Le Drian has said that a chemical or biological attack "was among the risks" in the wake of the 13 November attacks, but all precautions were taken to avoid such a scenario.

He said the authorities were not ruling anything out, even though it was "very complicated" for anyone to use chemical weapons.

Mr Valls had said on Thursday that an attack using such weapons was possible.

Yesterday, the French government authorised the army's pharmacies to distribute an antidote for chemical weapons to civilian emergency services.