A $4.2 billion deal to buy helicopters and missile defense systems from Russia has been canceled only weeks after it was signed, Iraqi officials say. The agreement, which was signed in October, was canceled over concerns about corruption, the BBC reported Saturday. The deal is now being investigated by Iraqi Prime Minister Nouri Maliki. Maliki\'s critics had questioned the deal, noting that Iraq had already signed multiple arms deals with the United States. The initial contracts for 30 Mi-28NE night/all-weather capable attack helicopters, and 50 Pantsir-S1 gun-missile short-range air defense systems were signed earlier this by Iraq\'s acting defense minister, RIA Novosti reported. Moscow has not officially commented on the cancellation. The purchases would have made Russia the second-largest arms supplier to Iraq behind the United States. Russia was the biggest arms supplier to Iraq during the reign of Saddam Hussein.