Pirates left the chemical tanker Pramoni and the vessel has set a course away from the coast, said EU spokesman Cmdr. John Harbour. An EU warship is monitoring the situation and all the crew were safe, he said.
The cash was bundled in a waterproof container, attached to a parachute and pushed out the back of a small plane. It is a common way of delivering the multimillion dollar ransoms the pirates demand.
Harbour could not give details on the ransom paid for the release of the tanker, which was seized on Jan. 1 with 24 crew members from China, India, Nigeria and Vietnam.
Graeme Gibbon Brooks, the managing director of Dryad Maritime Intelligence Service, said it was likely that pirate attacks would sharply increase in March, April and May as calmer weather was expected to make it easier to launch attacks.
Gibbon Brooks said that he expected to see more attacks taking place between 600 to 1,000 miles (960 to 1,600 kilometers) off the Somali coast, targeting ships traveling commonly used routes between the island nation of the Seychelles and the East African coast.
Naval patrols have had some success in cutting the rates of successful attacks in the Gulf of Aden, but maritime officials say the Indian Ocean is simply too big to effectively patrol.
Somali pirates currently hold at least six ships and more than 100 crew.