LONDON — Tensions are growing between British and French officials as unprecedented numbers of immigrants hoping to reach Britain amass across the English Channel in the French port city of Calais, focusing attention on the United Kingdom's immigration policy ahead of national elections in 2015.
"Calais has been taken hostage," said the city's deputy mayor and immigration chief Philippe Mignonet, who in part blamed a British-French agreement for burdening his city — and essentially extending Britain's border to French shores. "There are migrants who arrive each day, and each day some who succeed in getting to Britain."
Nearly 2,000 immigrants, mainly from Africa and the Middle East, have gathered in Calais, many of them fleeing war and poverty to seek asylum in the U.K. They are placing intense pressure on French resources, aid agencies and police as the asylum seekers clash amid overcrowding in illegal camps.
Britain has said it will not change its border control arrangement with France, which stipulates that immigration checks must be carried out before migrants board cross-channel ferries from sea ports in either country.
"The security of the U.K. border is our priority and juxtaposed controls help play a vital part in stopping those who have no right to be here from entering the U.K.," said a spokesman for the British Home Office, which is the government department responsible for immigration. "We are taking action at a national and international level to tackle this issue and the organized criminality behind illegal immigration."
Meanwhile, Mr. Mignonet announced last week that French authorities will be begin destroying a camp for illegal immigrants in Calais.
"The camp will be dismantled. All depends on the Home Office minister to give the instructions to do so," he told London's Daily Express newspaper.
The French immigration chief noted the allure of Britain's illegal labor market and London's cosmopolitan character in attracting immigrants in search of a better life.
"They might leave with three pounds, but when they arrive in England they can make 50 pounds a week on the black market," Mr. Mignonet said. "England is too attractive. It's too easy."
Immigration is expected to be a hot-button issue in next year's elections in Britain.
According to the U.K.'s Office for National Statistics, in the year ending March 2014, Britain received:
• 23,731 asylum applications — a 5 percent increase over the previous year.
• 156,378 work visa applications — a 10 percent increase.
• 219,053 study-related visa applications — a 6 percent increase.
Applicants for asylum mainly came from Eritrea, Syria and Albania, but asylum applications represent only a fraction of all British-bound immigration — which, in 2013, topped more than half a million migrants from the European Union and elsewhere, up from 498,000 the previous year.
As migrant numbers swell, analysts say the issue at Calais could become a flashpoint that reignites debate in a country where concern over immigration is particularly widespread.
"Concerns about the security of the border and immigration's association with asylum are often associated with more negative attitudes," said Scott Blinder, director of Oxford University's Migration Observatory.
"Since it has been on the agenda for polls and surveys, there [have] been pretty similar, high levels of opposition in terms of British people saying there is too much immigration and there should be less," Mr. Blinder added.
According to a 2013 poll conducted by the Migration Observatory, more than 50 percent of Britons thought there was too much immigration and more than 60 percent saw migrants as a problem and not an opportunity, compared to fewer than 30 percent of Swedes who felt the same way.
Mr. Blinder said negative attitudes could stem from politicians' framing of immigration as a "problem to be solved," as well as the effects of the recession and Britain's decision to open its labor market to new EU member states the Czech Republic, Estonia, Hungary, Latvia, Poland, Lithuania, Slovakia and Slovenia in 2004 before it had to do so.
"This is why Britain is exceptional to the rest of Europe. People consistently refer back to this as a huge mistake," Mr. Blinder said. "Eastern Europeans settled in a broader swathe of the country, not just in London, so that could have brought concerns to broader sections of the country."
A nation of more than 64 million people, Britain has an illegal immigrant population of more than 500,000, according to a 2005 study. With a per capita gross domestic product of about $37,300, Britain enjoys a strong economy and has communities from nearly every quarter of the world, making it an attractive destination for illegal immigration.
Overall, the number of people entering the U.K. has been greater than the number emigrating from the country since 1994, and Balanced Migration, a cross-political party group, projects Britain's population will reach 70 million by 2027 and that two-thirds of that growth will be a result of immigration.
The organization says this will place new pressures on schools, the state-run National Health Service and the police, and it is calling on the government to balance the numbers.
The British government did vow to reduce net migration — the difference between the number of people entering and leaving the country during the year — to the tens of thousands by the national election, but with current net migration levels at 212,000, this seems impossible.
Prime Minister David Cameron's Conservative government also has shifted focus from border security and pre-entry checks to in-country control with the 2014 Immigration Act. Immigrants now must pay a new health care levy, and landlords are responsible for checking their tenants' immigration status.
Ruth Grove-White, policy director at Migrants' Rights Network, said looking at immigration as a numbers-based issue is "missing the point."
"The achievements of migrants are embedded in the achievements of the nation — the role migrants play is integral to what it means to be British," said Ms. Grove-White.
"Immigration has made a huge contribution to the economic, cultural and social fabric of the U.K. Look at the contribution in the NHS, where up to 40 percent of nurses are migrants," she said.