Many leaders attending the meeting are lamenting the fact the food insecurity is not a priority. Other issues such as AIDS or climate change have taken precedence.
The new US Secretary of State Hillary Clinton was not present at the meetings, but gave a speech to the conference that she recorded in Washington DC.
The AFP has more on Diouf's comments at the world hunger conference.
The food crisis pushed another 40 million people into hunger in 2008, Jacques Diouf said here at the start of a two-day international conference on food security.
That brought the global number of undernourished people to 973 million last year out of a total population of around 6.5 billion, he said.
"We face the challenge now of not only ensuring food for the 973 million who are currently hungry, but also ensuring there is food for nine billion people in 2050. We will need to double global food production by 2050," he said.
But Diouf warned the global economic crisis was already undermining efforts to tackle food insecurity as it was making it harder for farmers to get loans to buy materials and new equipment that would boost yields.
"The current economic situation does not make our task easier," he said.
The fall in prices for certain food staples from last year's highs could also discourage farmers from sowing crops, adding to the difficulty in meeting FAO's goal to halve the number of people who live in hunger by 2015, he said.