German chemicals giants Bayer and BASF said Thursday they were teaming up to produce genetically modified rice seeds, technology than can boost yields but which is criticised by environmentalists.

The firms said they aim to develop and sell hybrid rice seeds with traits enabling yield advances of 10 percent or more over conventional hybrid seeds. The first products are expected to be launched by 2020.

Rice is the world?s largest food crop, with half of the world?s 6.8-billion population consuming at least one meal of it every day.

According the International Rice Research Institute (IRRI), an additional 8-10 million tonnes of rice needs to be produced each year to feed people and keep prices for the cereal at an affordable level, BASF and Bayer said.

Today, global rice production is about 685 million tonnes.

For many, GM crops, by which scientists create new strains of plants that do not occur naturally by manipulating genes, are the answer to feeding the world's rapidly growing population.

But opponents say that these genetically modified organisms (GMOs) can spread and interbreed with other plants, the consequences of which are unknown.

They also say that their use will increase the control of private companies over agriculture, with 10 corporations already controlling nearly 70 percent of the world seed market, according to pressure group Greenpeace.