ATHENS, Greece — Crewmen fired high pressure water jets today to fight off heavily armed Somali pirates trying to board a Greek oil tanker in the dangerous Gulf of Aden 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.