Nearly 150 nations plan to attend a signing ceremony for the global climate agreement at UN headquarters next week, France's environment minister Segolene Royal, the official overseeing the process, said on Friday.

"We have 147 confirmed to sign on April 22, including about 50 heads of state," said Royal, president of the UN climate change process told reporters at a press conference in Washington.

"That means that momentum for the Paris accord has not subsided," said Royal, referring to the international meetings last December where the agreement was hammered out by global leaders.

Royal said the ceremony should afford world leaders the opportunity to issue "a strong declaration" on carbon pricing policy.

The goal, she said, should be to set an "elevated, stable, discernible and coordinated" carbon price as a way to encourage the development of clear energy.

Under UN agreement, the host of the yearly climate COP (conference of parties) undertakes to make the event "climate neutral" by reducing emissions as much as possible.

At the Paris gathering -- dubbed COP21 for the 21st Conference of Parties -- almost 200 governments reached an agreement setting a target of limiting global warming to "well below" 2.0 degrees Celsius (3.6 Fahrenheit) compared to pre-industrial levels.

The historic agreement calls for a dramatic reduction in greenhouse gases, in a concerted effort to cap global warming at "well under two degrees Celsius" (3.6 degrees Fahrenheit) above the pre-industrial benchmark.

The deal only comes into force, however, if at least 55 countries responsible for at least 55 percent of global greenhouse gas emissions ratify the accord.

US President Barack Obama, who travels next week on a fence-mending trip with ally Saudi Arabia, will not be in attendance at the New York signing ceremony. His surrogate at the ceremony has not yet been announced by officials in Washington.