Gulf of Guinea pirates free Greek-operated tanker

* Crew safe after gasoline tanker hijacked

* Piracy common in West Africa's waters

ATHENS, Oct 9 (Reuters) - Pirates freed a Greek-operatedgasoline tanker on Tuesday that they had hijacked over theweekend in the Gulf of Guinea, the operator of theBahamas-flagged ship said, adding that the crew were all safe.

The tanker Orfeas, crewed by two Greeks and 22 Filipinos,had been expected to discharge 32,000 metric tonnes of gasolineat Abidjan, Ivory Coast. But on Saturday it sailed southeasttowards Nigeria with no explanation.

"Grace Management had lost contact ... last Saturday and itwas feared that the vessel had been hijacked. This has now beenconfirmed by the master," the operator said in a statement,adding that it had been released at 1030 GMT.

"All the crew members are safe and in good health."

The statement did not say whether the hijackers stole thefuel, as they normally would before releasing the boat.

Pirate attacks are on the rise in the Gulf of Guinea, whichis second only to the waters around Somalia for piracy. Fuelships are a favourite target, and the pirates are usually onlyinterested in the cargo, not the hostages.

Many of the criminal gangs in pirate networks are offshootsfrom militant groups that used to operate in Nigeria's oil-richNiger Delta before they agreed an amnesty in 2009.

In August pirates attacked a Greek-operated oil tanker witha crew of about 20 off the coast of Togo. They released the shipa few days later after stealing 3,000 tonnes of fuel.

(Reporting by Renee Maltezou; Writing by Tim Cocks)

((tim.cocks@thomsonreuters.com; +234 803 400 4248;))