By Emmanuel Jarry

PARIS (Reuters) - France plans to go ahead with a global climate change summit in Paris at the end of the month, the prime minister said on Saturday, despite a wave of deadly attacks on Friday night that killed 127 people in the capital.

The conference "will be held because it's an essential meeting for humanity," Prime Minister Manuel Valls told TF1 television on Saturday evening.

He said the summit would also be an opportunity for world leaders to show their solidarity with France after the attacks.

About 118 world leaders are expected to attend the opening day of the Nov. 30-Dec. 11 conference, which is due to nail down a global deal to limit rising greenhouse gas emissions.

In Washington, officials confirmed that both U.S. President Barack Obama and Secretary of State John Kerry still planned to attend.

Overall, between 20,000 and 40,000 delegates are expected to attend.

"Security at U.N. climate conferences is always tight but understandably it will be even tighter for Paris," said Nick Nuttall, spokesman of the U.N. Climate Change Secretariat in Bonn.

The United Nations has the main responsibility for security inside the conference venue at Le Bourget, to the north of the capital.

On Saturday, an angry President Francois Hollande promised a "merciless" response to the wave of attacks by gunmen and bombers that killed 127 people across Paris, describing the assault, claimed by Islamic State, as an act of war.

Organizers of a march to press for climate action planned for Paris on Nov. 29, the eve of the summit, said they would meet on Monday "to discuss ways forward", said Alice Jay, director of the citizens' campaign group Avaaz and one of the organizers.

Organizers have been hoping to imitate a "People's Climate March" in New York last year that attracted hundreds of thousands of people, the largest protest against global warming in history.

(Reporting by Emmanuel Jarry; writing by Leigh Thomas and Alister Doyle; Editing by Kevin Liffey and Hugh Lawson)