Biofuel subsidies came under attack on Tuesday at the opening of the United Nations food summit in Rome as the head of the UN's Food and Agriculture Organisation claimed that "nobody" understood the diversion of food to fuel cars. The opening salvo is likely to set the tone for the next three days and put countries such as the US and Brazil, the world's largest biofuel producers, and also the European Union, on the defensive over their support of biofuel production. Jacques Diouf, director-general of the FAO, told heads of state and government gathered in Rome that the "the problem of food insecurity is a political one." "Nobody understands how $1 lbn-$12bn a year on subsidies and protective tariff poli-' cies had the effect of diverting 100 million tonne of cereals from human consumption, mostly to satisfy a thirst to fuel for vehicles," Diouf said. He added that it was also difficult to explain how it was "not possible to find $30 billion a year [in agriculture aid from rich countries] to enable 862m people to enjoy the most fundamental of human rights: the right to food, and thus the right to life." "Nobody understands," Diouf added, "how the rich countries have created a distortion of world market with the $272 billion spent on supporting their agriculture." Speaking at the summit on Tuesday Luiz Inacio Lula da Silva, Brazil's president, rebuffed the biofuels criticism, saying that some lobbies want-; ed to create a "smoke screen blaming ethanol for the recent food inflation."The link be-, i tween biofuels and food prices,'1 Lula da Silva said, "does not stand up." "The increase of food prices. does not have a single explanation. It is a mix of soaring oil and fertiliser prices, climate, change, speculation, growing consumption in developing countries such as China, Inv dia or Brazil, and the absurd-protectionist [agriculture] policies of the rich countries." The spat over biofuels and the use of export bans is likely to concentrate discussions, at the summit, which is attended by more than 60 heads of state, and government, including Nicolas Sarkozy of France, and Mah-moud Ahmadi-Nejad of Iran. Wary of the conflict, Ban Ki-moon, the UN secretary-general, sought a more conciliatory tone in his opening speech, saying that the world needed to reach a "greater degree of consensus on biofuel policies." But in a document published on Tuesday, the UN task-force on food also said that the world needed to "reassess" subsidies and tariffs on biofuels. The US and Brazil have already started the run-up to the summit defending their biofuel policies. Ed Schafer, US agricul