Non-governmental experts and European officials are gathering in Paris Thursday for a conference about the rising phenomenon of human trafficking.   Lisa Bryant reports from the French capital that experts are calling for better monitoring and coordination to combat the problem, especially in cases involving children who have been the most vulnerable.

Experts estimate that about 2.4 million people are trafficked around the world each year, with the numbers rising. But that is only a rough estimate, they say, since getting a grip on the phenomenon is difficult.

But one thing is clear, according to Marina Leabsch, the number of people being trafficking around the world is increasing. Leabsch is an expert on human trafficking for the Catholic relief organization Caritas, which is organizing the Paris conference.

"According to the recent estimates of the International Labor Organization, we can see that half of the estimated people being trafficked are children, and since trafficking is a crime and a serious violation of human rights, it's clearly a concern," she said.

Leabsch says most of the human trafficking takes place in Asia - but about 250,000 people are trafficked each year in Europe and other industrialized countries.

"If we talk about [Europe], then we are certainly talking about countries like Ukraine, the Czech Republic, Lithuania - also all the Baltic countries, but also Russia," she said.

Experts like Leabsch say children are easy prey for traffickers in particular. In some cases their parents are tricked into believing they are sending their children to a better life in a richer nation.

Caritas and other groups fighting against human trafficking are urging the European Union to do more to monitor the phenomenon within individual member states and to establish more cross - border communication to combat it across the 27-member block.