NAIROBI, Kenya — Pirates chased and shot at a U.S. cruise ship with more than 1,000 people on board but failed to hijack the vessel as it sailed along a corridor patrolled by international warships, officials said Tuesday.

The captain of the M/S Nautica ordered passengers inside and gunned the engine, allowing the ship to outrun the pirates' speedboats in the Gulf of Aden on Sunday, a company spokesman said.

"It is very fortunate that the liner managed to escape," said Noel Choong, who heads the International Maritime Bureau's piracy reporting center in Malaysia. He urged ships to remain vigilant in the area.

In a statement on its Web site, Oceania Cruises, Inc. said pirates fired eight rifle shots at the liner, but that the ship's captain increased speed and managed to outrun the skiffs.

"When the pirates were sighted, the captain went on the public address system and asked passengers to remain in the interior spaces of the ship and wait until he gave further instructions," said Tim Rubacky, spokesman for Oceania. "Within five minutes, it was over," he said.

All passengers and crew are safe and there was no damage to the vessel, the company statement said. Rubacky said the ship planned to return through the Gulf of Aden.

Choong said the ship was carrying 656 international passengers and 399 crew members.

The International Maritime Bureau, which fights maritime crime, did not know how many cruise liners use the waters, where hijacking of freighters and tankers has become a constant threat in spite of patrols by an international flotilla.

The U.N. Security Council extended for another year its authorization for countries to enter Somalia's territorial waters with advance notice and use "all necessary means" to stop piracy and armed robbery at sea. Russian Ambassador Vitaly Churkin said the pirates' goals are "ever-expanding."

The U.S. Navy's 5th Fleet, based in Bahrain, said it was aware of the failed hijacking of the cruise ship — a sign of the pirates' growing ambition — but had no further details.

The Nautica was on a 32-day cruise from Rome to Singapore, with stops at ports in Italy, Egypt, Oman, Dubai, India, Malaysia and Thailand, the Web site said. Based on that schedule, the liner was headed from Egypt to Oman when it was attacked.

The liner arrived in the southern Oman port city of Salalah on Monday morning, and the passengers toured the city before leaving for the capital, Muscat, Monday evening, an official of the Oman Tourism Ministry said Tuesday. The official spoke on condition of anonymity because he was not authorized to speak to the media.