A Jet Airways Boeing 777-300, registration VT-JEV performing flight 9W-234 from Amsterdam (Netherlands) to Toronto,ON (Canada) with 320 people on board, was enroute at FL340 about 190nm northwest of Shannon about to enter the Oceanic Crossing when the crew reported they suspected a fuel leak on the left hand engine (GE90) and decided to divert to Shannon. The crew shut the left engine down, dumped fuel on the way to Shannon and landed the aircraft safely on Shannon's runway 24 about one hour later. The aircraft remained on the ground for about 5 hours, then was able to continue the flight and is estimated to reach Toronto with a delay of 6.5 hours.