Countries will have the right to restrict imports of genetically-modified (GM) foods under an international agreement reached at talks in Montreal.

The United States, Canada and four other grain-producing nations had argued that such limits would break the World Trade Organisation's free trade rules.

But after protracted negotiations, the 133 nations at the Montreal conference agreed that the new bio-safety protocol would have equal status with WTO regulations.

The argument for safeguards had come from the European Union and developing countries.

Breakthrough

After all-night negotiations, Colombian Environment Minister Juan Mayr announced the breakthrough agreement just before dawn.

"The adoption of this protocol represents a victory for the environment," Mr Mayr said, fighting back tears.

"But don't forget that this only represents the beginning. We have still before us a great challenge."

The agreement allows countries to restrict imports of GM products if they fear that these products may harm human health or get into the environment and damage it.

It covers foodstuffs, as well as seeds for farmers and feed for animals.

UK Environment Minister, Michael Meacher, said in a BBC interview that for the first time the principle of caution about GM foods was anchored in an international agreement. It provided a better balance between protection of the environment and free trade rules.

"On balance, we think this is an agreement that protects the environment without disrupting world trade," said David Sandalow, Assistant US Secretary of State for Oceans, Environment and Science.

Labelling

The deal was reached after intensive bilateral negotiations between representatives of the major exporters of GM products such as Canada and the United States, and negotiators representing the EU and the developing countries.

One sticking point had been US opposition to the European Union's proposals that all GM foods are labelled to alert consumers.

The two sides agreed that shipments of GM commodities should bear labels saying they "may contain" genetically-modified organisms and are not intended for intentional introduction into the environment.

The deal also requires countries to begin negotiations on more specific labelling requirements to take effect no later than two years after the protocol enters into force.

Talks over the treaty stalled in Colombia last February when the US, Canada, Australia, Uruguay, Argentina and Chile would not agree to a draft accepted by 125 other countries.

The two sides clashed again on the issue at the unsuccessful Seattle trade talks in December.

The Montreal negotiations started on Monday amid demonstrations by campaigners who believe that GM foods pose a health threat to humans and wildlife.