The Sydney Food Fairness Alliance coalesced around a number of issues that affect the city's food security, including the drought, climate change, population growth, urban encroachment on agricultural land and concerns about the health impact and embedded costs of industrially produced food.

One suggestion is the creation of a state-level ministry of food which would have oversight of all relevant food production, supply and distribution issues.

The alliance, founded in 2006, will host a summit on October 22 and 23, called Hungry for Change, at which it plans to weave together these concerns into a food charter that might form the basis of future government policy.

"It has been left for a long time to market forces, and the food system really requires much more long-term and integrated planning than has been there to date," said a summit organiser, Elizabeth Millen, of the South West Sydney Area Health Service.

Ms Millen also noted the huge public costs of diet-related problems such as type 2 diabetes and cardiovascular disease.

London, Vancouver and New York have adopted food policies in the past two years, and Toronto has had one for 10 years.

"We can't grow all our food locally: those 100-mile diets and so on are interesting experiments but they're not replicable in the city," said Russ Grayson, vice-president of the alliance, which includes health workers and nutritionists, researchers, local government, environmentalists, chefs, permaculture advocates and social justice groups from churches.

"But it's obviously sensible to have as much as we can grown locally … especially for a city coming up to 6 million by 2025."

Part of the summit's aim is to highlight grassroots steps already being taken around Sydney, such as backyard and communal gardens and "community-supported agriculture", where a group of city residents subscribe for a weekly box of produce from a small group of farmers.