Striking into the heavily patrolled Gulf of Aden, Somali pirates seized a British-flagged chemical tanker — the first merchant vessel to be hijacked there in nearly six months, the same day that a ship was taken by brigands in the Indian Ocean, officials said Tuesday.

The double hijacking late Monday shows that, a year after an international naval armada began deploying off Somalia to protect shipping, piracy remains a problem. Monday's attacks occurred more than 1,000 miles (1,600 kilometers) apart, indicating the wide range of territory prowled by pirates and underscoring the difficulty of policing such a large area. Cmdr. John Harbour, the spokesman for the European Union's anti-piracy force, said the seizures were likely only a coincidence and not coordinated because several pirate bands operate in the Indian Ocean and Gulf of Aden.

"Most of the time we are able to disrupt them, but sadly they were successful taking two ships at once. It's not the first time they've taken two ships at once," Harbour said. EU officials believe about 1,000 Somalis are involved in the piracy trade.

Somali pirates have hijacked more than 80 ships in the past two years, with many of the hijackings earning the pirates multi-million-dollar ransoms.

Resolving the hijacking of the British-flagged tanker could be complicated because the crew is comprised of nine nationalities, Harbour said.

With the latest hijackings, pirates now hold 12 vessels and 263 crew members, said Noel Choong, who heads the International Maritime Bureau's piracy reporting center in Kuala Lumpur, Malaysia.

A top official from Somalia's weak, U.N.-backed government urged the international community to pursue pirates in their havens on land.

"We have reiterated so many times that pursuing pirates on land is crucial to any military response," said Somali Information Minister Dahir Gelle. "

The U.K.-flagged tanker St James Park was the first merchant vessel to have been hijacked in the Gulf of Aden in nearly six months, Choong said. He said the ship issued a distress message Monday. A fishing boat was taken in the gulf earlier this month.

Lt. Cmdr. Corey Barker of the U.S. 5th Fleet in Bahrain said the guided missile cruiser USS Chosin responded to the alarm from the British tanker but that it came after pirates had already taken control of the ship.

"The first indication we got that the ship was pirated was that alert beacon," Barker said. "It's basically a panic button, a silent alarm."

Barker said the Chosin, the flagship for a U.S.-led anti-piracy task force in the region, was the nearest coalition ship to the British vessel. He estimated it was about 25 to 30 minutes away when the distress call came in.

Merchant vessels passing through the heavily patrolled corridor check in upon entry and then are tracked on their journey through, he said.

The St James Park had set sail from Tarragona, Spain, and was headed for Tha Phut, Thailand, Harbour said. The tanker has 26 crew members from the Philippines, Russia, Georgia, Romania, Bulgaria, Ukraine, Poland, India and Turkey, he said.

Three hours after the St James Park was hijacked a Panamanian-flagged carrier with 19 crew members was seized by pirates off the southern coast of Somalia. The ship is managed in Greece.

Greece's Merchant Marine Ministry said the Navios Apollon was carrying fertilizer from the U.S. to India. It was taken 240 nautical miles northeast of Seychelles, it said. The crew was comprised of one Greek and 18 Filipinos.

In another development, pirates released the Singapore-flagged container ship Kota Wajar on Monday, the EU Naval Force said. The vessel was hijacked in mid-October in the Indian Ocean with a crew of 21 on board.

Somalia has not had an effective central government since 1991 as regional warlords vie for power, and impoverished young men have increasingly taken to piracy in recent years in hopes of a big ransom payoff.

The latest incidents brought the number of attacks in the Gulf of Aden and off Somalia to 214 this year, with 47 vessels hijacked, Choong said. That compares to 42 successful attacks out of 111 attempts in 2008, before the EU Naval Force deployed in the Gulf of Aden in December 2008.

Pirates anchor their captured crafts off Somalia's shore near the pirate strongholds of Haradhere and Hobyo. International forces can't rescue the vessels without risking the lives of the crew, leaving negotiated ransoms as the only safe means of resolution.