The confrontation between foreign warships and well-armed pirates off the coast of lawless Somalia is a dramatic reminder to the Asia-Pacific region of the importance of safeguarding busy channels used by international shipping. Australian exports to Europe and North America through the Red Sea and the Suez Canal are affected.

Questions may also be asked about security in the Straits of Malacca and Singapore the shortest sea route between the energy-rich Persian Gulf and voracious energy consumers in north-eastern parts of Asia, especially China, Japan and South Korea that depend heavily on oil imported from the Middle East. However, the deteriorating situation off the Horn of Africa and potential threats to shipping in the Gulf provide a stark contrast to improved security in previously pirate-prone South-East Asian waters.

Reflecting the intensifying fighting and political chaos in Somalia where the central government collapsed in 1991, piracy directed at ships passing the country with the longest coastline in Africa has worsened. In recent months, more and more vessels have been attacked and hijacked. Using as much as $US30million ($A41million) in ransom money paid this year by ship owners to free their seized vessels and crews, the pirates have bought increasingly sophisticated equipment, including faster attack craft with longer ranges, rocket-propelled grenades, satellite phones and global positioning systems.

This has emboldened them to strike further from shore and move northwards into the Gulf of Aden, which links the Red Sea and Suez Canal to the Arabian Sea.

If the attacks continue, ships plying between the Asia-Pacific or Middle East and Europe-North America might have to divert around the Cape of Good Hope on the tip of southern Africa, as they did at great expense from 1967 to 1975 when the Arab-Israeli conflict closed the Suez Canal.

This would raise the cost of oil and other goods being shipped to the West, worsening the economic recession and financial turmoil gripping Europe and the United States. Already, insurance rates for ships passing Somalia have skyrocketed, as they did after al-Qaeda suicide terrorists drove a small boat packed with explosives into a laden oil tanker off the coast of nearby Yemen in 2002. Current international concern was galvanised when Somali pirates captured a Ukrainian freighter, the Faina, on September 25 about 320km off the coast of Somalia. The ship was heading for Kenya loaded with 33 Soviet-designed T-72 battle tanks, artillery, grenade launchers and other arms. With this booty estimated to be worth $30 million in their hands, pirates have demanded $20 million to release the ship and its 20 crew members.

They deny any connection with terrorists. But a US-led naval flotilla surrounding the Faina, now anchored off the coast of central Somalia, says it will not allow the arms to fall into the hands of an al-Qaeda-linked Islamic movement battling Somalia's Government and forces from neighbouring Ethiopia that were sent in to protect it. As a Russian warship steamed towards the crisis zone, the Somali Government last week authorised foreign powers to use whatever force is necessary to free the Faina.

The episode shows how a small but well-armed and determined group of pirates from a failed state can menace an important international shipping lane despite the deployment of warships by global powers. The US-led task force patrolling off Somalia says it has deterred 12 pirate attacks in the Gulf of Aden since the end of August. But there have been more than 50 attacks around Somalia this year and over 25 have resulted in successful hijackings, according to the anti-piracy arm of the International Chamber of Commerce. A dozen ships and 259 seafarers are being held hostage at present, a situation that prompted a call by the global shipping community last month for an effective crackdown by governments and their naval forces.

Around 90 per cent of world trade by volume is carried by ships, with some 50,000 merchant vessels trading internationally. They carry everything from steel containers of manufactured goods to bulk commodities like oil, coal and wheat. Although these ships roam the oceans, most of them follow fixed maritime routes that pass through a series of geographic ''chokepoints'', or narrow channels. Chokepoints are vital because so much of the world's trade passes through them, yet they are narrow and could be blocked, at least temporarily, by inter-state conflict, terrorism, pirate attacks and shipping accidents.

Among the main chokepoints for international trade in energy and other goods are the Straits of Malacca and Singapore in South-East Asia, the Hormuz Strait, which is the only way by sea into and out of the Gulf, and the Bab el-Mandab Strait, which connects the Red Sea and the Gulf of Aden. About 20,000 ships transit the Gulf of Aden each year, only about one-third of the number using the Straits of Malacca.

A United Nations Security Council resolution in June gave permission to nations to send warships into Somalia's territorial waters to stop piracy and armed robbery at sea, provided such action was taken in cooperation with the beleaguered Somali Government in Mogadishu. Several years ago, as international concern mounted over pirate attacks in and around the Malacca Straits, the governments of countries flanking the waterway Singapore, Malaysia and Indonesia pre-empted any possibility of UN or foreign intervention by taking action to reduce piracy and safeguard shipping.

They launched coordinated sea patrols in 2004, combined air patrols a year later, and improved intelligence exchange in 2006. Last month, Thailand became the fourth country to join the Malacca Straits patrols, which are backed by an anti-piracy agreement among regional governments and an associated information-sharing centre based in Singapore.

There is room for improvement, of course. Although pirate attacks in South-East Asian waters are down, they still occur. In the past few days, there have been ship robberies in the South China Sea, not far from the Malaysian resort island of Tioman. But the Maritime Bureau of the International Chamber of Commerce, which runs a piracy reporting network for the shipping industry, acknowledges that the number of pirate attacks in the Malacca Straits has dropped because of increased patrolling by the littoral states.

The writer, a former Asia editor of the International Herald Tribune, is an energy and security specialist at the Institute of South East Asian Studies in Singapore.