Free trade in agricultural markets can undermine attempts to ease poverty in developing countries and harm the environment, says a UN and World Bank backed report.

"Opening national markets to international competition ... can lead to long-term negative effects on poverty alleviation, food security and the environment," says the International Assessment of Agricultural Science and Technology for Development (IAASTD) report.

The report urges agricultural science to pay greater attention to safeguarding natural resources.

It promotes 'agro-ecological' practices, such as the use of natural fertilisers and traditional seeds and reducing the distance between the farm and the consumer.