Prime Minister John Key is scheduled to land in Trinidad late tonight for the Commonwealth summit, where United Nations Secretary-General Ban Ki-Moon will make a personal plea for leaders to also attend climate talks in Copenhagen in 10 days.

United States President Barack Obama yesterday said he would attend the start of the talks and that the US emissions reduction target would be 17 per cent of 2005 levels by 2020. Wen Jiabao, the Chinese premier, also said he would be attending.

Mr Key was last night sticking to his position that he is unlikely to go, but he has left the door open.

Asked what it would take, he said "If I thought a deal was going to be concluded, and at this stage it seems very unlikely."

He was speaking in Hawaii on his way to Trinidad.

Mr Key's RNZAF flight, with the leaders of three other countries, Tonga, Samoa and Vanuatu, was delayed several hours as checks were made to a suspected fault in the Boeing 757 carrying their delegations and reporters.

The summit is likely to be dominated by climate change and pre-Copenhagen diplomacy.

In a highly unusual move, French-Anglo rivalry is taking a backseat as French President Nicolas Sarkozy is tipped to make an appearance at the meeting of 53 countries after attending a special meeting of eight Amazon countries in Brazil.

He will join Denmark's Prime Minister Lars Lokke Rasmussen, Mr Ban and UN climate change chief Yvo de Boer in a session on climate change.

In some respects it may be a rerun of the Apec summit in Singapore two weeks ago, where Mr Rasmussen briefed 21 leaders before talks he will host in Copenhagen in 11 days for a treaty to succeed the Kyoto protocol.

The bloc of countries in Trinidad won't be as high-powered as Apec, but with 53 member it is still a large and important grouping, many of whose small island members are most affected by climate change.

The aim of the Rasmussen sessions is to adjust expectations of what can occur at Copenhagen - not that an agreement can be concluded there but that it is the first of a two-step process.

Small developing countries are not expected to make binding commitments in the agreement, but some commitment is expected from the large developing countries including India which is a Commonwealth member.

Commonwealth Secretary-General Kamalesh Sharma in speech in Trinidad this week described this Chogm as a "crisis summit".

"How times have changed since the last People's Forum in Kampala, Uganda," he said.

"We have all had a bad few years: of crisis upon crisis. The fuel and food crises of last year have been compounded by a financial crisis in 2009, in which no less than half of our members are suffering negative growth.

"Everyone is hurting - there is a strong case for saying that Chogm 2009 constitutes a crisis summit."

Climate Change Negotiations Minister Tim Groser welcomed the session on Copenhagen, saying it should have happened six months ago.

"The recalibration of expectations about Copenhagen has been left dreadfully late."

Mr Rasmussen was doing the right thing in going to Chogm to talk about the need for a strong and binding agreement along his formula of "one agreement, two steps".

Mr Groser said he had told the Cabinet in February that there was no possibility of a full and final ratifiable agreement being concluded at Copenhagen.

"We should be welcoming what he is doing because instead of essentially running the risk of a train wreck, there is now a serious possibility of some big political and politically binding decisions being taken on some key elements of the deal."

It will be Mr Key's first Chogm. He will use the summit to promote New Zealand's proposal for a global alliance on research into agricultural emissions, a proposal he launched in New York in September.

Mr Key will be hoping to spend some time with India Prime Minister Manmohan Singh to discuss the free trade talks which are expected to start early next year.

The situation in Sri Lanka was discussed by the Commonwealth foreign ministers who have met over the past two days and that may be put on the leaders' agenda too. Australia has been active in getting the issue on the Commonwealth agenda because boats of asylum seekers heading to Australia have been intercepted.

Amnesty International this week called on the Commonwealth to address the human rights issues in Sri Lanka - the conditions of the camps for displaced people after the end ofthe civil war there six months agoand what it calls the obstruction of organisations trying to help.

Sri Lanka was to have hosted the next Chogm in two years, but has withdrawn. Australia is offering to host it in Perth, pitching itself as another Indian Ocean host.