US President George W Bush has called on world leaders to increase pressure on Burma's rulers, as US officials moved to ban imports of Burmese gems... The measure, passed by the House of Representatives, tightens sanctions against the junta by attempting to stop gem dealers from laundering their goods in third countries before they enter the US... Democratic Rep Tom Lantos said in a statement: "Burma's generals fund this repression of their own people by selling off the country's natural resources..., leaving the Burmese people in poverty."