DAVID Cameron's description of migrants trying to reach Britain as a "swarm" has been condemned as "disgraceful" by Andy Burnham and "irresponsible" by the Refugee Council.

The Labour leadership candidate suggested the Prime Minister was stooping to the worst kind of dog-whistle politics by using the term, which is usually associated with insects.

Mr Cameron used the emotive language as he discussed measures being taken to deal with chaotic scenes at Calais, where large numbers of migrants living in a tent city have attempted to enter the Channel Tunnel.

Speaking during a visit to Vietnam, he argued that the problem had become worse in recent months because "you have got a swarm of people coming across the Mediterranean; seeking a better life, wanting to come to Britain".

Mr Burnham was swift to condemn the remark, tweeting: "Cameron calling Calais migrants a 'swarm' is nothing short of disgraceful. Confirms there's no dog-whistle these Bullingdon Boys won't blow."

Nigel Farage also distanced himself from the term, suggesting it was part of an effort by the PM to appear "tough" on immigration.

Asked if he would use the word "swarm", the Ukip leader told the BBC: "No. No, I'm not seeking to use language like that. The Prime Minister is this morning trying to sound tough. Whether he actually means it or not is quite a separate question."

Meantime, the Refugee Council described Mr Cameron's remark as "awful, dehumanising language from a world leader".

Lisa Doyle, it's head of advocacy, said: "It's extremely disappointing to hear the Prime Minister using such irresponsible, dehumanising language to describe the desperate men, women and children fleeing for their lives across the Mediterranean Sea.

"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," she added.