London - Britain risked a "xenophobic response" to the migrant crisis in the French port of Calais, a senior United Nations official warned on Thursday, after Prime Minister David Cameron promised to deport more migrants who enter Britain illegally.Demands for the British government to keep out economic migrants are "a xenophobic response to the issue of free movement", Peter Sutherland, the UN secretary general's envoy on international migration, told the BBC.Facing a "very testing" situation, Britain will deport more illegal migrants "so people know it's not a safe haven", Cameron told reporters in Vietnam.He said Britain and other European nations faced a "swarm of people coming across the Mediterranean, seeking a better life".But Sutherland said such claims were "exaggerated and calculated to inflame tensions with regards to the numbers trying to come into Britain"."Last year the total approval of refugees coming into France was 68 000, which is more than twice the figure of the UK," Sutherland told Irish broadcaster RTE."There should be a fair allocation across EU countries," he said.Germany received 175 000 asylum applications last year, compared with 24 000 for Britain, Sutherland told the BBC."We are talking here about between 5 000 and 10 000 people in Calais who are living in terrible conditions," he said.Opposition politicians and the London-based Refugee Council also criticised Cameron.Acting Labour leader Harriet Harman accused him of using "inflammatory language", while Labour leadership candidate Andy Burnham called his comments "disgraceful"."We are talking about human beings here, not insects," said Liberal Democrat leader Tim Farron, referring to Cameron mentioning a "swarm of people"."This sort of rhetoric is extremely inflammatory and comes at a time when the government should be focused on working with its European counterparts to respond calmly and compassionately to this dreadful humanitarian crisis," said Lisa Doyle, the Refugee Council's head of advocacy."Britain has a proud tradition of protecting refugees," Doyle said. "It's important that tradition is safeguarded in times of crisis."Hundreds of migrants stranded in Calais continued efforts to reach the Channel Tunnel linking the two nations for a fourth day early on Thursday.The British and French governments on Wednesday vowed to tighten security around Calais following the ninth death of a migrant in the past five weeks on Tuesday.A 16-year-old Egyptian migrant was electrocuted and suffered life-threatening injuries after he climbed onto the roof of a British-bound train on Wednesday at the Gare du Nord station in Paris, the France Info website reported.Interior Minister Bernard Cazeneuve said on Wednesday that France will deploy 120 extra police officers in Calais but added that operator Eurotunnel, which reported intercepting 37 000 migrants this year, "must also take responsibility" for improving security.Europe is facing "an exceptional migration crisis... [with] tragic human consequences," Cazenueve said, reporting nearly 230000 illegal entries to the EU's Schengen nations from the Horn of Africa, Syria, Iraq and Afghanistan this year."Calais is a mirror of the conflicts and crises tearing some regions of the world apart," he said, urging "resolute action from the European Union".