The impact of climate change has been a major source of dispute

Agreement has been reached among delegates at a major conference on climate change in Brussels.

A final accord was struck after delays caused by disagreement over the likely impact of global warming.

"What we have is a very good document," said Rajendra Pachauri, chairman of the Intergovernmental Panel on Climate Change (IPCC).

The report is expected to say climate change is already having major impacts on the natural world.

The panel believes there is also a discernible, though less marked, impact on human societies.

The details are due to be unveiled at a news conference shortly.

Objections

Scientists and government officials from more than 100 countries met through the night, trying to agree on the wording of a summary for policy makers.

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The report's authors say the document shows global warming is having a major impact.

"[The report] says quite clearly that climate change is happening and it is having effects on ecosystems and society, with particularly bad effects on developing countries.

"So it is quite a bleak message but it's now up to governments to act on what we told them," said Richard Klein of the Stockholm Environment Institute.

The report will be sent to world leaders in time for a G8 summit of industrialised nations in June.

It is the second in a series of IPCC reports coming out this year, together making up its fourth global climate assessment.

The first element, on the science of climate change, released in February, concluded it is at least 90% likely that human activities are principally responsible for the warming observed since 1950.

The third part, due in May, will focus on ways of curbing the rise in greenhouse gas concentrations and temperature.