The Christian development agency Tearfund has expressed its disappointment at the outcome of the UN Climate Change Conference in Nairobi as international leaders failed to produce either a plan to agree a global target for reducing greenhouse gas emissions, or an adequate timetable to reach agreement on cuts.

This was a "regrettable failure of political will," it said.

It added that, despite 11th-hour negotiations in Nairobi by ministers from around the world, the final outcome from the Conference "charts the weakest of paths" towards rich countries cutting global emissions after the first phase of the legally-binding Kyoto Protocol ends in 2012.

"Despite strong lobbying by the EU, including the UK, to achieve a better outcome, a comprehensive deal could not be struck. This is a blow to efforts to avert dangerous climate change," said Tearfund's Andy Atkins.

Slow progress during the conference prompted Tearfund to criticise the lack of urgency among conference delegates earlier in the week. As the conference drew to a close on Friday the feeling remained the same.

"Sadly, this conference has been marked by a lack of urgency and leadership. This must change quickly if we are to halt global warming in the decades ahead," he said.

One step forward came at the last minute when leaders agreed that a review of the Kyoto Protocol will be held in 2008. The review will open up many of the Protocol's measures, which could in future contribute towards deciding new emissions targets, and to more money flowing to developing countries.

"The decision came late, but it was a positive step," said Rachel Roach, Policy Advisor for Tearfund.

Another key issue facing negotiators from the 189 countries related to the need for funding to help developing countries cope with climate change.

Ms Roach called upon key international leaders to wrap up some of the unfinished business from Nairobi before the next UN conference in 2007: "There were steps in the right direction towards finalising details of a special fund to help developing countries adapt to climate change, but key decisions, including which body will manage the fund, were postponed until next year's conference.

"At this conference it was encouraging to see much greater awareness of climate change as a key poverty issue, but overall it is not acceptable to leave African soil without more decisions to benefit poor people. Some progress was made, but high level political weight must now be thrown behind outstanding issues before the next UN conference in 2007."