Nigeria's anti-narcotics agency is working with its U.S. and British counterparts to investigate the origins of a $235 million cocaine shipment seized at Lagos' Tincan Port, in one of the country's largest drug hauls.The National Drug Law Enforcement Agency (NDLEA) said in a statement on Tuesday that 1,000 kg of cocaine was discovered in an empty container at a terminal over the weekend. Terminal operators alerted the NDLEA and other port security agencies, which jointly examined…