The tragedy at Dover is far from an isolated event in Europe and remarkable mainly on account of the number of people who died.

According to Jean-Phillipe Chauzy of the Geneva-based International Organisation of Migration (IOM), such deaths are literally a daily occurrence on the Continent.

"Since January of this year, almost 160 people have been drowned, or their bodies have been found in the Straits of Gibraltar, people coming from the Maghreb or sub-Saharan Africa. The fact of the matter is nobody really knows how many people die each year attempting to be smuggled across borders. It's safe to say at least one person dies every day of the year," he said.

German border authorities say that cramming immigrants into containers, as at Dover, is a common practice on its eastern borders and that any hiding-place in a truck that can be used to smuggle cigarettes or alcohol can also conceal human cargo.

The discovery of larger groups of migrants being moved across Europe's borders has convinced the authorities that the smugglers are increasingly professional in their organisation, changing routes and methods frequently and quickly.

Some international organisations distinguish between trafficking and smuggling migrants, but most now accept that the boundary between voluntary and involuntary migration is often blurred.

Promises of good jobs are often used to dupe potential migrants to pay large sums to agents who seldom warn of the dangerous nature of the enterprise, both in transit and when the migrant arrives.

Many illegal migrants are exploited by the smuggling gangs on arrival, put to work in sweatshops or as sex workers.

Only a minority of the most desperate migrants, usually young men, feel compelled to use the services of the smugglers. Overstaying is by far the most common form of illegal migration.

Although the IOM favours tough action against the criminal gangs in human trafficking, Mr Chauzy argues that western European governments ought to address the causes of such migration.

"It's pretty obvious that if people had economic options in their country of origin, if they could eat three times a day, they probably wouldn't be rushing to get on boats and into containers to go to countries where they can. If more means were made available for people to migrate regularly for labour, irregular migration would not be so popular," he said.

Italy has just introduced an initiative that will allow 5,000 Albanians to work in the country for one year, on condition that they are not accompanied by their families and that they return home at the end of that period. An extensive poll conducted in central and eastern Europe last year found that few people, even in the poorest regions, want to work abroad for more than a few months at a time.

The tightening of border controls at the periphery of the EU that followed the introduction of the Schengen Agreement between some member-states may have driven greater numbers of migrants into the arms of the human traffickers.

Schengen abolished border controls between participating states but obliged those states to reinforce their external borders.

The German authorities are full of praise for Poland's attempts to control illegal migration, but Warsaw is reluctant to tighten its border controls with Ukraine and Belarus as Brussels is demanding as a condition for Poland's EU membership.

Germany and Britain are the most popular destinations for human traffickers, with France and Italy often serving as transit routes. There is no evidence that the Republic is being targeted.

Mr Chauzy believes the key to controlling migration is to create a dialogue between the countries and he advises the Irish authorities to work towards that end.

"This problem cannot be solved in a one-sided way. You've got to be able to have a reasonable level of dialogue with the sending countries. That also applies to those returning because deporting people is one thing but if you don't give them economic prospects at home, they'll probably come back," he said.