Concentrations of the main greenhouse gases in the atmosphere have reached their highest level since pre-industrial times, the World Meteorological Organization (WMO) said on Wednesday.

Concentrations of the gases continued to build up in 2009 -- the latest year of observations -- despite the economic slowdown, the U.N.

"The trends in disasters, particularly from climate change, are of enormous concern," said John Holmes, U.N. undersecretary-general for humanitarian affairs.

"We can only expect that this kind of trend is going to continue," he told a news conference.

The Mortality Risk Index was issued by the U.N. International Strategy for Disaster Reduction (UNISDR) before a four-day meeting of the Global Platform for Disaster Risk Reduction opening on Tuesday at which 1,800 officials and experts will examine natural catastrophes.

Chemicals producers and governments agreed on Friday to step up efforts to push for greater safety in chemicals from lead in paint to microscopic substances.

But non-governmental organisations (NGOs) said unless the industry and governments come up with more money, agreed targets for cleaning up chemicals by 2020 were unlikely to be met.

One year after Cyclone Nargis devastated a swathe of Myanmar, and with the monsoon rains setting in once more, survivors need increased international aid to prevent more deaths, the United Nations said on Tuesday.

Cyclone Nargis swept across Myanmar's Irrawaddy Delta and southern Yangon on May 2, 2008, killing nearly 140,000 people and displacing 2.4 million.