French President Jacques Chirac has again urged world leaders to impose a levy on airline tickets to finance extra aid for Africa, his office said on Tuesday. Chirac, who told the World Economic Forum in January that a tax of $1 per airline ticket could raise $10 billion a year to fund campaigns against diseases in Africa, pressed his case in a letter he wrote to more than 140 world leaders, according to Reuters. "I offer you to associate yourselves with the establishment of an international solidarity contribution on plane tickets, aimed, particularly, at financing the fight against AIDS, tuberculosis and malaria," he said in a letter dated Monday. In the letter addressed to state leaders such as Russian President Vladimir Putin and British Prime Minister Tony Blair, Chirac said the tax would be imposed on tickets of planes leaving from airports in participating countries. Chirac urged world leaders to work on the proposal ahead of the United Nations' summit in September. "If the September summit allowed to launch this project, it would constitute a historic moment of hope, of mobilisation and action, and I would be happy if your country could participate in this," Chirac wrote.