(Adds increased estimate of migrant numbers, reaction to plan)
By William James
LONDON, July 14 (Reuters) - Britain plans to create a 'secure zone' at the French port of Calais to protect lorries heading for England from migrants trying to enter the country illegally, interior minister Theresa May said on Tuesday.
Migrants fleeing war, political turmoil and poverty make daily attempts to board lorries and trains heading for Britain, drawn by family ties, a growing economy and a perception that the British system treats migrants better than other countries.
The problem has been exacerbated in recent weeks by a French ferry workers' strike that blocked traffic around the port. British police on Tuesday raised their estimate of the number of migrants in Calais to 5,000 from 3,000.
May said the secure waiting area would hold 230 vehicles, the equivalent of a 2.5-mile (4 km) queue of traffic.
"This should transform protection for lorries and their drivers - removing them from the open road where they can become targets for migrants attempting to board their vehicles," May said in a statement to parliament.
May said that over 8,000 attempts by illegal migrants to enter Britain were successfully intercepted by border authorities between 21 June and 11 July.
May's office said the zone would be policed by French authorities and was expected to be operating before December. It would replace an existing 90-lorry waiting area, and be set up behind established fences, which French and British authorities are working to improve.
But the plan was not seen as a permanent solution by trade organisations and Eurotunnel, the company operating the rail link under the channel.
"As soon as you remove an opportunity, the organised criminals who are managing the migrant attacks are moving to the next opportunity, to the next weak spot," said John Keefe, director of public affairs at Eurotunnel, told a parliamentary inquiry into the situation at Calais.
Richard Burnett, chief executive of the Road Haulage Association, said the overall cost of migrants trying to board vehicles could be as much as 1 billion pounds ($1.56 billion) per year because many hauliers have to destroy cargo on board breached lorries.
"We need action now, we need something in place right now. We can't afford to wait," Burnett said, speaking to the inquiry.
Responding to the criticism, immigration minister James Brokenshire said the secure zone was one of many measures the government and French authorities were implementing to tighten security around the Calais ports, some of which would be completed by the end of the month. ($1 = 0.6423 pounds) (Editing by Larry King)