JOHANNESBURG (Reuters) - French President Jacques Chirac will urge world leaders to launch talks on a new international tax to fight world poverty, sources with him at the Earth Summit in Johannesburg say. The sources said Chirac rejected the existing "Tobin Tax" proposal to raise levies purely on foreign exchange transactions but would call in a speech to the summit for discussion on a wider tax on wealth generated by globalisation. "It could be a tax on airplane tickets, on carbon dioxide, on health products sold in industrialised countries, and indeed on international financial transactions," one source said. "The idea...