Environmental activists are claiming victory over the United States as more than 100 countries agree to rules on the export of genetically modified (GM) products.

Signatories to the UN's Cartagena Protocol on Biosafety, which came into force last September, decided at a conference on a "rigorous system" for handling, transporting, packaging and identifying GM crops, food and other exports.

The agreement "foiled attempts by the USA and other GM-exporting countries to weaken this newborn international agreement on GMOs," the Friends of the Earth environmental group said.

The US has not signed the protocol, which has been ratified by 86 countries and the European Union.

The country lobbied hard on the sidelines of the conference for minimal labelling of GM products, claiming they posed no threat to human health or the environment.

Critics, however, have dubbed such products - known as genetically modified organisms (GMOs) or living modified organisms (LMOs) - "Frankenfoods", after the monster Frankenstein.

The US is the world's biggest producer of GM crops and is already involved in a battle over export regulations in the World Trade Organisation.

"GMOs pose a real danger to the environment and to the health and livelihoods of people around the world," said Friends of the Earth International spokesman Juan López.

Under the new system, all bulk shipments of GM crops intended for food, animal feed or processing, such as soybeans and maize, are to be labelled.

The common, scientific and commercial names of the organism along with the "transformation event code" must be documented, as well as the contact details of the traders, while handling and storage requirements must be clearly indicated.

Shipments of GMOs such as seeds and fish that are meant to be introduced directly into the environment must be clearly identified as "destined for contained use", provide contact details in case of emergency, identify the GMO's risk class and specify how it is to be used.

"Now that a system for identifying and labelling GMO exports has become operational, countries can enjoy the benefits of biotechnology with greater confidence while avoiding the potential risks," said Hamdallah Zedan, the protocol's executive secretary.

"This rigorous system for handling, transporting, packaging and identifying GMOs is in the best interests of everyone - developed and developing countries, consumers and industry, and all those who care deeply about our natural environment," he said.