Methyl bromide is highly toxic to humans and damages the ozone layer, a stratospheric shield against the sun's ultra-violet rays, which cause skin cancer and cataracts.

It is used to fumigate high-value crops, for pest control and in quarantine treatment of agricultural exports.

In 1987, some 180 countries signed the so-called Montreal Protocol, to phase out by January 2005 some 100 ozone-depleting chemicals, including methyl bromide.

Adherence to the protocol promises in 50 years to reverse ozone-layer damage, UNEP said.

The agreement was reached under the auspices of the United Nations Environment Program.

Granting limited exemptions to the protocol's "increasingly strict controls will ensure that the transition to ozone-friendly solutions does not cause farmers and other users of methyl bromide undue economic pain," said UNEP executive director Klaus Topfer.

Britain, Australia, Belgium, Spain, Greece, Italy, the Netherlands and Portugal are also seeking an exemption.

A three-day meeting of the Montreal Protocol on Substances that Deplete the Ozone Layer starts here on Wednesday.

Participants will consider granting exemptions to the countries so that they can use the pesticide for certain "critical uses" after its scheduled phase-out date, the UNEP said in a statement.

The Montreal Protocol allows governments "to apply for exemptions when there are no technically or economically feasible alternatives or for health or safety reasons," the UNEP statement said.

TERRA.WIRE