Lawrence Chukks, 35, who hails from Lagos in Nigeria, was arrested on August 14 when he was asked by the complainant businessman to come over at Kanjhawala to receive some money from him, police said.
A passport and a forged ID have been seized from him, they said adding that an FIR under various provisions of the IPC for offences of cheating, faking identity and forgery has been registered against him.
The FIR said that the trader received an e-mail from the gang that the Health Ministry of Nigeria was floating a tender for supply of one lakh T-shirts to promote breast feeding in the country.
"On the pretext stamp duty, registration fee, attorney fee, bond deposit, money transfer fee and money conversion fee the cheaters induced him (the trader) to transfer money to the tune of Rs 50 lakh", it said.
The complainant, who got alarmed, approached the police which advised him to keep in touch with the cheats, police said, adding that the accused, posing as a Nigerian diplomat, got entrapped when when he came to meet the trader for finalizing the deal.
Further investigation is going on to arrest other co-accused, police said.