COPENHAGEN - Danish Prime Minister Lars Loekke Rasmussen on Thursday officially invited 191 heads of state and government to the United Nations' climate summit in Copenhagen in December, his office said in a statement.
Denmark's official invitation marks an additional push on global leaders to attend the much anticipated conference.
"Your personal attendance is a pivotal contribution to a successful outcome of the United Nations Climate Change Conference," Rasmussen wrote in the invitation.
"Our joint efforts will be judged by the citizens of the world on December 18 when we close the conference."
The invitations were sent to United Nations member countries via Denmark's diplomatic missions.
During preparatory talks held in Barcelona last week, UN climate chief Yvo de Boer urged world leaders to attend the Copenhagen summit.
"I have never before witnessed a moment in time when this issue has been so high on the agenda of world leaders," he told reporters.
"We must capitalise on that in Copenhagen by inviting world leaders to give the Copenhagen outcome the final push and get us to a result," he urged.
De Boer said "even though a formal invitation (had) not yet been issued" by Denmark, 40 heads of state and government already considered coming to the conference, including British Prime Minister Gordon Brown, French President Nicolas Sarkozy and Brazilian President Lula Inacio da Silva.
UN climate conferences are usually attended by environment ministers rather than heads of state and government, but the stakes in Copenhagen are such that world leaders have been urged to attend.
UN chief Ban Ki-moon strongly encouraged all heads of state and government to attend the key talks in Copenhagen.
Ban "believes that direct head of state and government involvement is essential for governments to reach agreement on the core issues at the heart of a global climate change deal," a UN statement said.
"The Secretary-General believes it is essential to maintain political momentum at the highest level and from all sectors of society, and is optimistic that an ambitious, fair and effective climate deal can be reached at Copenhagen," it added.
Environmental group Greenpeace also lauded the official invitation by Rasmussen for a dinner on December 17 and a meeting on December 18.
"Some heads of state have been ducking the question about going to the Copenhagen Climate Summit by saying no formal invitation has come from Denmark. That excuse is now gone," Greenpeace Denmark spokesperson Tove Ryding said in a statement.
Ryding added "40 heads of state including UK Prime Minister Gordon Brown have said they are coming. Now President Obama must respond with a positive RSVP," the statement said.
The Copenhagen marathon is designed to climax a two-year process of negotiations leading to a worldwide agreement for tackling climate change beyond 2012.
The talks have been mired in discord over how to share out the burden for curbing greenhouse-gas pollution and to prime a financial pump to help developing countries switch to a low-carbon technology and adapt to climate change.