Food security and the rapid rise in food prices make up the "elephant in the room" that politicians must face up to quickly, according to the government's new chief scientific adviser.

In his first major speech since taking over, Professor John Beddington said the global rush to grow biofuels was compounding the problem, and cutting down rainforest to produce biofuel crops was "profoundly stupid".

He told the Govnet Sustainable Development UK Conference in Westminster: "There is progress on climate change. But out there is another major problem. It is very hard to imagine how we can see a world growing enough crops to produce renewable energy and at the same time meet the enormous increase in the demand for food which is quite properly going to happen as we alleviate poverty."

He predicted that price rises in staples such as rice, maize and wheat would continue because of increased demand caused by population growth and increasing wealth in developing nations. He also said that climate change would lead to pressure on food supplies because of decreased rainfall in many areas and crop failures related to climate. "The agriculture industry needs to double its food production, using less water than today," he said. The food crisis would bite more quickly than climate change, he added.

But he reserved some of his most scathing comments for the biofuel industry, which he said had delivered a "major shock" to world food prices. "In terms of biofuels there has been, quite properly, a reaction against it," he said. "There are real problems with unsustainability."

Biofuel production is due to increase hugely in the next 15 years. The US plans to produce 30bn gallons of biofuels by 2022 - which will mean trebling maize production. The EU has a target for biofuels to make up 5.75% of transport fuels by 2010.

But Beddington said it was vital that biofuels were grown sustainably. "Some of the biofuels are hopeless. The idea that you cut down rainforest to actually grow biofuels seems profoundly stupid."

Before taking over the chief scientist post from Sir David King nine weeks ago, Beddington was professor of applied population biology at Imperial College London. He is an expert on the sustainable use of renewable resources.

Hilary Benn, the environment secretary, said at the conference that the world's population was expected to grow from 6.2bn today to 9.5bn in less than 50 years' time. "How are we going to feed everybody?" he asked.

Beddington said that in the short term, development and increasing wealth would add to the food crisis. "Once you move to [an income of] between £1 a day and £5 a day you get an increase in demand for meat and dairy products ... and that generates a demand for additional grain." Above £5 a day, people begin to demand processed and packaged food, which entails greater energy use. About 2.7bn people in the world live on less than £1 a day.

There would also be increases at the higher end of the wage scale, he said. At present there are 350m households on £8,000 a year. That is projected to increase to 2.1bn by 2030. "It's tremendous good news. You are seeing a genuine prediction from the World Bank that poverty alleviation is actually working."

But he cautioned that the increased purchasing power would lead to greater pressure on food supplies. Global grain stores are currently at the lowest levels ever, just 40 days from running out. "I am only nine weeks into the job, so don't yet have all the answers, but it is clear that science and research to increase the efficiency of agricultural production per unit of land is critical."

Beddington's in-tray

Animal diseases

Surveillance for bird flu, foot and mouth disease, bovine TB, bluetongue and others will need to be maintained.

Nuclear power

The chief scientist will have a key role in implementing the policy to plug the energy gap when existing power stations reach the end of their lives.

Severn barrage

The government is reviewing the feasibility of a tidal barrage in the Severn estuary which could provide 5% of the country's energy needs.

GM crops

Senior government sources hinted last year that they wanted to expand the planting of GM crops.

UK astronauts

The government has all but closed the door on the prospect of a UK astronaut corps in the near future. But there is still a strong lobby for it from some scientists as a way to enthuse the public about science.