(IDEX Online) - Allegations of a $200m rough diamond and foreign exchange scam involving customs officers in Mumbai are being investigated by India's Directorate of Revenue Intelligence (DRI), the Free Press Journal reports.The Mumbai-based newspaper says the DRI stumbled upon corrupt "hawala" transactions - money transfer without money movement - allegedly carried out with the connivance of staff at the Precious Cargo Customs Clearance Centre (PCCCC) at Bharat Diamond Bourse (pictured).The allegation is that consignments of rough diamonds were "round-tripped" - imported at inflated cost, under-invoiced for re-exporting and then imported again at inflated costs.The newspaper it had seen documents indicating diamonds were imported at highly exaggerated value "to siphon off excess foreign exchange overseas to cover the differential cost of imports of other goods like electronic devices and park black money abroad".It said the DRI probe revealed that diamond traders, in connivance with customs officers, had inflated imports of rough diamonds to more than $200m in an 18-month period.