A decline in the diversity of farmed plants and livestock breeds is gathering pace, threatening future food supplies for the world's growing population, the head of a new United Nations panel on biodiversity said on Monday.

Preserving neglected animal breeds and plants was necessary as they could have genes resistant to future diseases or to shifts in the climate to warmer temperatures, more droughts or downpours, Zakri Abdul Hamid said.

"The loss of biodiversity is happening faster and everywhere, even among farm animals," Zakri told a conference of 450 experts in Trondheim, central Norway, in his first speech as founding chair of the U.N. biodiversity panel.

Many traditional breeds of cows, sheep or goats have fallen out of favour, often because they yield less meat or milk than new breeds. Globalisation also means that people's food preferences narrow down to fewer plants.

Zakri said there were 30,000 edible plants but that just 30 crops accounted for 95 percent of the energy in human food that is dominated by rice, wheat, maize, millet and sorghum.

He said it was "more important than ever to have a large genetic pool to enable organisms to withstand and adapt to new conditions." That would help to ensure food for a global population set to reach 9 billion by 2050 from 7 billion now.

Zakri noted that the U.N.'s Food and Agriculture Organization estimated last year that 22 percent of the world's livestock breeds were at risk of extinction. That means there are fewer than 1,000 animals in each breed.

The extinctions of some domesticated animals and plants was happening in tandem with accelerating losses of wild species caused by factors such as deforestation, expansion of cities, pollution and climate change, he said.

Irene Hoffmann, chief of the FAO's animal genetic resources branch, told Reuters that eight percent of livestock breeds had already become extinct.

Many nations had started breeding programmes for rare livestock, from llamas to pigs. Some were freezing embryos or even stem cells that might be used in cloning, she said.

In 2010, governments set goals including halting extinction of known threatened species by 2020 and expanding the area set aside in parks or protected areas for wildlife to 17 percent of the Earth's land surface from about 13 percent now.