NAIROBI, Kenya -- Five Somali pirates are jailed for life by a U.S. court. Sixty-one suspected pirates captured at sea face trial in India. Somali prisons are running out of room.

Pirates captured at sea by international navies used to be routinely set free because no country wanted the hassle and expense of a court case. But as piracy has flourished and turned increasingly violent, an unprecedented 17 countries are prosecuting pirates in courts around the world.

The increase in arrests and prosecutions shows a growing recognition of the global problem piracy has become, said Alan Cole, the head of the U.N.'s anti-piracy program.

In recent months, six hostages have been killed -- including four Americans on a hijacked yacht -- and pirates have begun using explosives and blow torches to cut crews out of the secure rooms they sometimes retreat to during attacks.

"Piracy is becoming quite a high-risk enterprise," said Cole. "We see pirates in prison in Kenya, the Seychelles and Maldives. They are amazed to come in and see their cousins, brothers and friends in there. They thought they had all made it and gone to open shops in Europe. The recruiters are lying to them."

Seventeen nations have put more than 850 pirates on trial in the past year and a half, Cole said, including five Somali pirates given life sentences in a U.S. court on Monday. Before the five were convicted late last year, the last U.S. conviction for piracy was in 1819.

A U.S. federal judge was set to decide Tuesday whether 14 more suspected pirates should remain in jail while awaiting trial on charges of piracy, kidnapping and firearms charges in the February yacht hijacking that left the four Americans dead.

In Somalia's semiautonomous region of Puntland, Cole said, authorities were releasing some low-level criminals to make room for pirates in the overcrowded jail in the port city of Bosasso. The U.N.'s Office on Drugs and Crime was funding a prison extension of 200 beds to help hold the extra prisoners, he said.

But attacks are increasing, not decreasing.

That's partly due to pirates' changing tactics. They are using captured vessels as "motherships" -- a mobile base from which to launch small attack skiffs. The hostages become human shields, preventing warships from intervening, said Cmdr. Paddy O'Kennedy of the European Union Naval Force.

On Sunday night, the Indian navy attacked the fishing boat Vega 5, which had been used as a mothership, in self-defense. Sixty-one pirates were captured and were being taken to Mumbai, India's financial capital, to be prosecuted.

O'Kennedy said that because pirates are now using motherships they can now launch attacks during the northeastern monsoon, which was prohibitive when pirates only used smaller skiffs.

During the monsoon in January 2010, there were 7 piracy incidents. In January 2011 that number shot up to 37, he said.

O'Kennedy said only 93 suspected pirates had been sent to court out of 770 pirates detained by the EU Naval Force since it began keeping records in December 2008. Many countries will not try suspects for conspiracy to commit piracy, because suspects captured with weapons and ladders often cannot be tied to a specific attack.

Even if countries are willing to try pirates, many are not willing to jail them. Thomas Winkler, an official from the Danish Foreign Ministry who helps coordinate the international response to piracy, said that although Somali courts might not be able to handle all piracy cases, Somalia was the natural place for pirates to serve their jail terms.

"The main challenge is not about courtrooms, it is about where they can serve their jail terms," he said. During a meeting in Copenhagen last month, U.N. officials suggested that the Somali region of Puntland and the breakaway republic of Somaliland build more jails to accommodate pirates convicted outside the country.

Last month, the island nation of the Seychelles, whose fishing and tourism industries have been hard hit by piracy, reached a deal to begin repatriating captured Somali pirates to their home country. It also changed its law last year to allow the prosecution of pirates who attack non-Seychelles-flagged ships, provided the flag country consents.

The state counsel in Seychelles, Michael Mulkerrins, said his country is prosecuting pirates because the scourge has had a "huge impact" on the economy.

Winkler also said Somali pirates should serve jail terms in Somalia, where they may be able to be rehabilitated. But he said trials must be held overseas.

"It is necessary to prosecute them outside Somalia because our sailors and ships are attacked," said Winkler. "While we are waiting the stability to return to Somalia, we have to prosecute them outside Somalia."

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Associated Press writer Malkhadir M. Muhumed contributed to this report.