ATHENS, Greece — Crewmen fired high pressure water jets to fight off heavily armed Somali pirates trying to board a Greek oil tanker in the dangerous Gulf of Aden on Friday in the fourth such attack since the start of the year, authorities said.

The pirates in three speedboats and armed with guns and rocket-propelled grenades twice tried to board the Greek-flagged Kriti Episkopi but were scared off when the crew turned fire hoses on them and EU aircraft scrambled from a nearby EU naval flotilla to help, company and Greek government officials said.

The attack came a day after Somali pirates seized an Egyptian cargo ship and its 28 crew in the vast waterway, one of the world's most important sea routes, where incidents have continued after 111 attacks in 2008. A Malaysian military helicopter on Thursday saved an Indian tanker from being hijacked and a French warship thwarted an attack on a Panamanian cargo ship.

The captain of the Kriti Episkopi spotted the speedboats just before 8 a.m. GMT approaching his ship and took evasive action to try to shake them off.

He contacted the Greek authorities who alerted the EU naval flotilla which swiftly scrambled an airplane and helicopter, the Greek Merchant Marine Ministry said.

"An aircraft and a helicopter reached the ship very quickly, which scared the pirates off," a ministry spokesman said, on customary condition of anonymity. "A frigate also sped to the scene. Everything now seems to be under control, but we remain vigilant."

The 29 crew members were unhurt and the tanker, carrying oil from the Persian Gulf to Greece, was not damaged in the attack off the pirate-infested Somali coast, said a statement by the ship's operating company Avin International.

"The ship is continuing its journey to its port of destination," the company said.

More than a dozen warships are now patrolling between the shores of Yemen and Somalia to try to protect commercial vessels. Countries as diverse as Britain, India, Iran, the United States, China, France and Germany have naval forces in the waters.

A French warship on Thursday intercepted two speedboats carrying eight Somali pirates as they were preparing to board the Panamanian ship, said a statement released late Thursday by the office of French President Nicolas Sarkozy.

The crew of the "PM L'Her" dispatch boat seized weapons and munitions on board. The French navy will hand over the men to Somali authorities.

Pirates successfully hijacked 42 ships in the Gulf of Aden in 2008. Of those, 14 are still in the hands of pirates with more than 240 hostages, according to the International Maritime Bureau.

The pirates have been given a free hand to operate because of more than a decade of turmoil in Somalia. The nation of about eight million people has not had a functioning government since warlords overthrew a dictator in 1991 and then turned on each other.