Food is fast becoming one of the defining political issues of this century. In June the G20 held its first ever agricultural ministers summit in Paris to discuss rising food prices and the impacts of commodity trading. Similarly, the OECD and UN Food and Agricultural Organisation (FAO) last month published a new report saying that high prices are here to stay.

The UN predicts cereal prices could average as much as 20 per cent higher over the next decade compared with the last 10 years. This is a theme picked up by Oxfam, who launched a new campaign on sustainable food stating that the price of staple crops could double over the next 20 years, creating more misery for communities struggling to survive.

The challenge for G20 is set out a credible plan of action to deal with global prices and the needs of developing countries. The final communiqué from agricultural summit urged finance ministers to improve the rules and supervision of commodity markets, far short of the crackdown on speculators which Nicolas Sarkozy had campaigned for. This is something that G20 Finance ministers need to address when they meet in July. We urgently need to understand and measure the extent of speculation on commodities before governments can decide how to take international action to address the problem. I recently met with Ross Warburton, Executive Director of Warburton's bakers who have the largest bakery in Europe in Wakefield. We discussed food commodity trading. He told me that bakers to need to hedge their position on flour, but why do bankers?

In the UK families are feeling the squeeze from rising food prices, which reached a two year high in May. Rising oil prices cause higher food prices as fertiliser and transport costs increase. Despite the recent rain, the South East has just had the driest spring on record. The worst winter for 100 years followed by the drought in the south and east of England and torrential rain in Scotland is creating havoc for crops. A recent NFU survey estimates that 15% of the cereal harvest has already been wiped out by the dry weather.

Politicians can't change the weather, but we can plan for it. It does, however, require political leadership. Yet the Tory-led Government is silent on these issues. They can't decide whether food production is the sole preserve of the free market (give or take £3 billion a year in CAP subsidies) or if there is a role for regulation. Peter Kendall, President of the National Farmers Union, has criticised Ministers for their lack of a national food plan. The Sustainable Development Commission - before the Government abolished it in March - called on them to 'stop thinking it (food) is someone else's responsibility'. Food and farming are completely absent from the Government's so-called sustainable development strategy.

Labour is challenging the Government on food. We reflect the growing consensus across the country on the need for a sustainable food policy. The only long-term solution is to increase the productivity of food production and to make it more resilient to a changing climate. The Government should be investing in the future of food yet it is cutting research and development, and increasing tuition fees which will deter new research scientists. The Government is cutting its R&D budget into efficiency in the food chain by 61% (down from £3,291,000 in 2011/11 to. £1,271,000 in 2014-15) over the next four years.

In Government, Labour commissioned the Foresight report, published this year, which examined the challenges of how to feed 9 billion people by 2050 while reducing the climate impacts of agriculture. A more sustainable food system should aim to create more reliable food supplies, less susceptible to price hikes, to everyone's benefit. Labour also produced Food 2030 which sets out how Government can help ensure everybody has the chance to eat safe, healthy, affordable and sustainable food, now and in the future. The Foresight review and Food 2030, the first national food strategy for 60 years, are our building blocks to a sustainable and equitable food system.

The UK has come a long way since I presented my Children's Food Bill to Parliament in 2006. Nearly seven hundred thousand people signed the Fish Fight petition calling for an end to the disgraceful practice of discards. A petition of over half a million people caused a Government u-turn on plans to sell off England's public forests. When Heads of State and government attend the G20 summit in November we need to ensure that they are aware of our desire for action on sustainable food.

We need food security at home and abroad, and greater transparency in how food commodities are traded globally, as Oxfam and others are calling for. People power helped fuel a rethink on the Common Fisheries Policy through the work of Hugh Fearnley-Whittingstall and Channel 4's Fish Fight campaign; now we need to do the same on food.

Mary Creagh MP, is the Shadow Secretary of State for the Environment Food and Rural Affairs.

Follow Mary Creagh on Twitter: www.twitter.com/marycreagh_mp