The growing use of armed guards on merchant ships plying the piracy-plagued waters of the Arabian Sea and the Indian Ocean has spawned increasingly violent encounters with Somali marauders, maritime security experts say.

This development illustrates how the pirate menace, which a few years ago was limited to the Gulf of Aden between Somalia and Yemen, has grown, and with it a maritime security industry that embraces at least 120 companies, more than half of them British, that provide protection for many of the 40,000 vessels that sail those waters every year.

The Financial Times reports the violent encounters at sea "could become more common as some shipping companies have reduced ships' speed through the highest-risk area to save on fuel."

Quoting maritime industry officials in London, the business daily reported: "The shipping companies have switched to relying on guards, rather than speed, for protection because a single-day at lower speeds can save $50,000 in fuel at current prices -- enough to pay the guards for the whole journey."

Ron Widdows, chief executive officer of major ship owner Rickmers Holding of Germany, said several security firms had suggested his company employ armed guards and slow down their ships.

But he asserted Rickmers was opposed to ordering vessels to reduce speed on the grounds doing so would only make them more vulnerable to attack by pirates using speedboats.

"The speed reductions contravene published advice that ships should use their maximum speed in the high-risk zones," the Financial Times observed.

These include the southern approaches to the Strait of Hormuz, the gateway to the Persian Gulf used by heavily laden supertankers.

These vessels have become prime targets for ransom by the pirate gangs over the last couple of years as they've extended their operations up to 1,500 nautical miles eastward as far as the coast of India.

Pirates have never been able to board a merchant ship traveling at 18 knots or more, and container ships and other faster vessels invariably have sailed through the most dangerous zones at up to 24 knots.

So, the maritime security business seems to be booming as governments increasingly sanction armed guards for their merchant vessels.

Some officials in the shipping industry are concerned that deploying teams of armed guards on ships will only drive the pirates to increase their firepower and that the emerging maritime security industry, still considered to be poorly regulated, could lead to potentially lethal battles at sea.

Judith van der Merwe, of the African Center for the Study and Research of Terrorism in Algiers, noted in April the increasingly sophisticated Somali pirates have acquired modern weapons from Libya, where military arsenals were plundered by rebels during the country's eight-month civil war in 2011.

These include U.S.-made Stinger shoulder-fired anti-aircraft missiles and sea mines.

"We found that Libyan weapons are being sold in what's the world's biggest black market for illegal gun smugglers, and that Somalia pirates are among those buying from sellers in Sierra Leone, Liberia and other countries," she explained.

The emerging maritime protection industry earns around $52.2 million a month from more than 1,500 escorted voyages from the Red Sea to the Indian coast, the Financial Times reported.

The nascent industry's earnings pale compared with the cost to the global shipping sector from piracy: $7.2 billion to $12 billion a year.

The One Earth Future Foundation in Colorado, which monitors piracy, reports shipping companies paid $160 million in ransoms for the return of hijacked ships, their cargoes and crews.

Meanwhile, shipping companies shelled out $1.1 billion on security equipment and armed guards and $635 million on insurance, the report noted. Crews also got an extra $195 million in danger money.

Naval task forces made up of U.S., European, Japanese and Chinese warships have hounded the pirates, thwarted some attempted hijackings and on some occasions rescued kidnapped crews.

But they've also driven the pirates deeper into the Indian Ocean, 2.5 million square miles of sea where the naval forces -- rarely more than 16 ships -- are too thinly stretched to provide effective protection.

"What we're seeing is a decrease in the number of successful attacks, but an increase in the ransoms paid out and the fear that better-armed pirates could risk more or pose a greater challenge," van der Merwe said.