The next time you buy some lingerie, a T-shirt or a pair of rubber gloves, you may want to reflect on this: they were probably made in Sri Lanka. And, like it or not, your purchase plays a role in the debate over how to respond to the Sri Lankan Government's successful but brutal military campaign against the Tamil Tiger rebels, which reached its bloody climax this week.

Since 2005 Sri Lanka has been allowed to sell garments to the European Union without import tax as part of a scheme designed to help it to recover from the Boxing Day tsunami of 2004. That means its clothes are 10 per cent cheaper than those from China and other competitors – helping the island to earn at least $2.9 billion (£1.9 billion) from the EU annually. Britain accounts for much of that.

Britain has also helped to rebuild Sri Lanka's tourist industry: Britons accounted for 18.5 per cent of the foreigners who visited the former colony's famous beaches, wildlife parks, tea plantations and Buddhist temples last year. Only India sends more tourists. Many Britons also own property there, especially around the southern city of Galle, not far from where Arthur C.Clarke, the British science fiction writer who settled in Sri Lanka, used to love to scuba dive.

So the question facing British shoppers and holidaymakers is this: should they continue to support Sri Lanka's garment and tourist industries? Sadly, the answer must be no.

Britain should welcome the defeat of the Tigers, a ruthless terrorist organisation that forcibly recruited children, pioneered the use of the suicide bomb and killed thousands of innocent people. But Britain must also condemn the Sri Lankan Government's conduct of the war – and take punitive action against it both to discourage other states from using similar methods, and to encourage proper reconciliation between the Tamil and Sinhalese communities. With the UN paralysed, economic sanctions is the only practical option left.

Many will ask why they should care: there are bigger conflicts in the world, and Sri Lanka's is mercifully confined to its own shores, with no risk that British troops might be deployed.

The response to that is simple: what about next time? Sri Lanka's war has been discrete only because it is an island; many other conflicts have spilt across borders, forcing military intervention to prevent a humanitarian disaster or a greater conflagration. Consider the break-up of Yugoslavia or Sierra Leone.

Britain may have, in the eyes of the world, ceded much of the moral high ground over human rights when it shed civilian blood during the invasion and occupation of Iraq. But that does not mean that it should abandon its role in defending international law that protects civilians in conflicts and holds governments accountable for their actions during war.

Yes, international humanitarian law is based largely on Western values, and enforced imperfectly, but the world would be a much more violent, unjust place without it. Put simply, every war might look like Sri Lanka's.

In an ideal world the UN, not the EU, would take the lead. But the UN, even in the face of a clear humanitarian disaster and blatant war crimes by both sides, has been compromised. By cosying up to China, Russia and other countries facing their own separatist problems, Sri Lanka managed to keep its own war off the formal agenda of the UN Security Council until the last minute. Without the UN Security Council's backing, an independent war crimes investigation will struggle to get off the ground.

Thus it is once again up to the democratic world to take action – even if that means muddling the issues of trade and human rights.

A key point to bear in mind is that human rights are an explicit part of GSP Plus, the EU's scheme that gives preferential trading rights to 16 developing nations, from Guatemala to Mongolia. These nations must comply with 27 international conventions covering environmental, labour and human rights standards. Many have gone to great lengths to adhere to them.

That may sound like excessive EU bureaucracy, but the system is designed to ensure the products we import meet EU standards – no child labour, for example. It is also designed to give developing countries an incentive to improve their own standards to the benefit of their own people.

That is where Sri Lanka has let itself down. Last year the EU expressed grave concerns about human rights abuses committed during the conflict and said that it might not renew the GSP Plus deal after it expired in December.

Sri Lanka's response was to dismiss the EU out of hand, accusing it of violating Sri Lankan sovereignty. The EU then announced that it was launching an investigation into possible rights abuses, pending the results of which GSP Plus remains in place. Sri Lanka has so far refused to co-operate, banking on EU inaction.

Since then, the situation has deteriorated dramatically. Sri Lankan armed forces are now suspected of repeatedly shelling civilian targets including hospitals, and of shooting dead at least two Tiger leaders as they were surrendering. They have also herded more than 200,000 Tamils into internment camps, splitting up families. These squalid places have insufficient water or medical supplies, and aid workers have been blocked from helping in these camps. Even the Red Cross has been forced to suspend its operations in the barbed-wire facilities, which the Sri Lankan Government calls “welfare villages” but Tamil activists liken to concentration camps.

Renewing GSP Plus in these circumstances would make a mockery of human rights and set an awful precedent for other nations. Withdrawing it could cost Sri Lanka 2 per cent of its GDP and thousands of jobs, which will hit many innocent civilians. But the fault, if this happens, will lie with its Government for failing to address the EU's concerns.

As to whether Britons should visit Sri Lanka as tourists, well that's a matter of personal choice – just as it is whether to visit Burma. But until the international community pulls together and formulates its own robust response, there is no clearer way for individuals to register their disapproval for the actions of Sri Lanka's Government than simply to stay away.

Jeremy Page is South Asia correspondent

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