Updated

ABOARD THE CARLSKRONA (AP) — A Russian warship hunted down an oil tanker hijacked by Somali pirates and special forces rappelled on board Thursday, surprising the outlaws, who surrendered after a 22-minute gunbattle. Twenty-three Russian sailors were freed.

The dramatic Indian Ocean rescue came a day after pirates seized the tanker, which was heading toward China carrying $50 million worth of crude. One pirate was killed and 10 others were arrested, officials said.

The Russian destroyer Marshal Shaposhnikov had rushed to the scene following Wednesday's seizure of the Liberian-flagged tanker, Moscow University.

After spotting the hijacked vessel early Thursday, the warship fired warning shots from its large-caliber machine gun, undeterred by the tanker's flammable cargo of 86,000 tons of crude.

Oil tankers don't even allow crew members to smoke on board because of the risk of igniting the cargo, but the Russian navy decided to move in with weapons after determining the crew had taken refuge in a safe room.

"The Marshal Shaposhnikov came near the tanker and after establishing contact with the crew, who were taking cover in the machine area of the ship, opened warning fire from large-caliber machine guns and a 30mm artillery complex," the Russian Defense Ministry said.

Special forces troops then rappelled down to the tanker from a helicopter, Rear Adm. Jan Thornqvist, the EU Naval Force commander, told an Associated Press reporter aboard the Swedish warship Carlskrona, which was patrolling 500 miles (800 kilometers) west of the rescue site.

The startled pirates opened fire and a gunbattle ensued that killed one pirate and wounded three before the hijackers surrendered, the Russian state news channel Rossiya-24 said. Russian Defense Ministry spokesman Col. Alexei Kuznetsov said a large weapons cache was seized.

The operation's success was due to the surprise factor, said a Russian military officer aboard the warship. "The pirates were taken by surprise. They did not expect such resolute measures from us," Capt. Ildar Akhmerov told RUA Novosti news agency.

The decision to free the ship was made knowing "that the crew was under safe cover inaccessible to the pirates" and that sailors' lives were not in danger, said the ship's owner, Novoship, which is a subsidiary of a government-owned company, Sovcomflot.

Safe rooms, where crews seek shelter, are typically stocked with food, water and communications equipment and have reinforced doors that can only be opened from the inside. Still, at one point, the crew had reported that they believed the pirates were trying to enter the engine room, Thornqvist said.

The raid shows that some governments are taking a more robust stand against pirate attacks, especially when their citizens are involved, said Graeme Gibbon Brooks of Dryad Maritime Intelligence in Britain.

Rescue attempts are easier when crews are locked away and not among the pirates, he said, though military action on oil tankers can be dangerous.

"As for whether live ammunition and oil tankers mix, really it's obvious there's a risk," Brooks said. "In terms of the decision to conduct the assault, these things are always a balance of risk versus benefit."

International military forces have been more aggressively combating piracy, which has flourished off the coast of lawless Somalia into a multimillion-dollar industry.

EU Naval Force ships are disrupting pirate groups and destroying their ships at a much higher rate than in previous years. U.S. warships have fired back on pirates and destroyed their boats in several skirmishes in the last several weeks.

Russian President Dmitry Medvedev congratulated the special forces for a job done "correctly, professionally, quickly," and sailors' relatives praised the rescue effort.

"It all ended so well that one has a warm feeling of pride for our country," said Ludmila Kotzenko, a sailor's mother.

The pirates were to be taken to Moscow to face criminal charges and Medvedev hinted at tough punishment.

"Perhaps we should get back to the idea of establishing an international court and other legal tools" to prosecute pirates, he said. "Until then, we'll have to do what our forefathers did when they met the pirates."

Cmdr. John Harbour, a spokesman for the EU Naval Force, called Thursday's rescue "an excellent operation all around." He said the EU force had been working at a tactical level with the Russians, and had talked to the Russian crew by VHF radio and offered support.

In February, Danish special forces prevented the hijacking of a ship after pirates boarded it. Special forces from the Danish Absalon boarded the Ariella while the crew locked themselves in a secure room.

Still, pirates are holding more than 300 hostages taken from ships off East Africa in the last several months.

The U.N. office on Drugs and Crime said this week that the island nation of Seychelles would establish a regional center for the prosecution of piracy. The court will accept the transfer of suspects from the EU Naval Force, while a joint EU-U.N. program will help ensure the country's police, prosecutors, courts and prisons have adequate resources.

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Associated Press writers Jason Straziuso in Nairobi and David Nowak and Mansur Mirovalev in Moscow contributed to this report.