NAIROBI, Kenya (AP) – Using flares and hoses, the crew of a Greek oil tanker fought off a pirate attack Tuesday in the Arabian Sea two days after brigands seized a tanker bound for the United States with $20 million of crude oil.

Pirates fired automatic weapons at the Sikinos and its crew of 24 some 500 miles (800 kilometers) southeast of Oman, according to a Greek coast guard statement. The crew fired flares and used high-pressure hoses to repel the attack and the vessel was continuing toward China.

The coast guard said the 16 Filipino and eight Greek seamen on board were unhurt. The Sikinos had set off from Sudan with a shipment of oil.

The Maran Centaurus, which pirates boarded on Sunday, is headed toward Somalia's coast. The attacks highlight the difficulty of keeping ships safe in the region – particularly oil tankers.

Crews on oil tankers aren't allowed to smoke above deck, much less carry guns, for fear of igniting the ship's payload.

And the Maran Centaurus – traveling from Saudi Arabia to New Orleans – had no escort because naval warships patrolling off the Horn of Africa are stretched too thin. The problem has been further exacerbated because pirates are now operating hundreds of miles out at sea, using mother ships for their skiffs.

Some ships, like the one that fought off the attack Tuesday, have been outfitted with high pressure water guns and piercing noisemakers to repel pirates. But even this is shunned on many oil tankers for fear of triggering a response from pirates armed with guns and rocket-propelled grenades.

"If you're not allowed to smoke a cigarette on the upper deck of an oil tanker, why would you want someone with a weapon up there?'' said Graeme Gibbon-Brooks, who heads the private security company Dryad Maritime Intelligence.

There is also the fear that a gunfight could cause a leak that would devastate the environment.

Twenty percent of global shipping – including 8 percent of global oil shipments – is funneled into the narrow, pirate-infested Gulf of Aden that leads through the Red Sea to the Suez Canal. The route is bordered on one side by the failed state of Somalia and on the other by the increasingly unstable country of Yemen.