France has formally announced plans for voluntary nutrition labels on food, including proposals for manufacturers to have the option of using traffic-light labels.

The proposals were published as part of a public health bill to be debated in the French Assembly at the start of next year.

Plans for the traffic light scheme on packaging were first announced earlier this year amid criticism that current labels were poorly displayed and difficult to understand.

"Nutritional information must be clear and I want to make labels on products more comprehensible so that consumers know the impact of what they buy on their health," said French Health Minister Marisol Touraine.

She said one of the aims of the new scheme was to "reduce social inequalities in terms of access to balanced eating".

The new labeling code would also be part of the effort to combat obesity. "Obesity has many causes and one of them is inadequate knowledge of the composition of food," Touraine added.

The practical workings of the system will be drawn up by the state food protection agency, ANSES.