MOSCOW, July 18 (RIA Novosti) - At least five large groups of pirates, totaling over 5,000 people, are operating in the Gulf of Aden, the first deputy chief of the Russian Navy General Staff said on Saturday.

"Pirates have become more daring and aggressive recently - there were instances when they seized vessels right in front of the ships that were responsible for the security of commercial shipping," Vice Admiral Oleg Burtsev said in an interview on Ekho Moskvy radio station.

According to the United Nations, Somali pirates collected $150 million in ransom payments from ship owners last year, while overall losses from piracy were estimated at $13-16 billion, including the soaring cost of insurance and protection for vessels, as well as sending ships on longer routes to avoid high-risk areas.

Somali pirates said on Saturday they had released a German ship after receiving a ransom of $1.8 million. The German Foreign Ministry confirmed that a German-owned ship had been released.

Around 35 warships from the navies of 16 countries are currently deployed off Somalia's coast to counter frequent pirate attacks on vital commercial lanes.

The Russian Navy joined international anti-piracy efforts off Somali coast in October 2008. Three warships have so far participated in the mission - the Baltic Fleet's Neustrashimy (Fearless) frigate, and the Pacific Fleet's Admiral Vinogradov and Admiral Panteleyev destroyers.

A new task force from Russia's Pacific Fleet, comprising the Admiral Tributs destroyer with two helicopters, a salvage tug, a tanker, and a naval infantry unit, will arrive in late July in the Gulf of Aden to join the operations.

Russia is also setting up a permanent investigation mission in the Gulf of Aden to participate in international efforts to fight piracy at sea off Somalia.

The head of the Investigation Committee at the Russian Prosecutor General's Office, Alexander Bastrykin, told reporters on July 3 that the investigators "will open criminal cases and conduct probes into crimes committed by pirates in order to arrest them and put them on trial under Russian law.