Yvette Cooper will next week propose a new “humane” asylum policy as she accuses the Government of turning away refugees from Britain because of its widely-criticised immigration target.

The shadow Home Secretary and Labour leadership contender will argue that people who are granted asylum should no longer be included in the target. The Government has pledged to cut net migration to under 100,000 a year but figures published on Thursday put it at 330,000 in the 12 months to March.

Police have arrested 27 suspected illegal immigrants found inside a lorry at a motorway service station at Cobham Services on the M25 in Surrey. The lorry driver was also detained. Sean Ingham, a trucker, said he saw the suspected illegal immigrants standing outside an Italian-registered refrigerated trailer.

Yvette Cooper, Labour Party leadership candidate speaks at an event in central London (AFP)

Ms Cooper is worried that the Home Office’s target encourages a tough line when it considers the plight of desperate refugees from countries such as Syria, where 4m have fled the civil war, and Eritrea, where the Government has been accused of crimes against humanity.

She told The Independent: “The Government’s net migration promise is not just dishonest, it's deeply damaging for Britain's approach to refugees. Including refugees and asylum seekers in the target is immoral. It treats those fleeing persecution or conflict in the same way as people coming to work or see family - and it gives the Home Office an incentive to refuse refugees in order to get the numbers down because they are failing to meet the target they set.”

She added: “Now that target is in tatters, and it acts as a shameful barrier to Britain fulfilling its role of offering sanctuary to some of the world’s most vulnerable. The Government should admit its mistake, scrap the target, and replace it with a more sensible system that completely separates immigration and asylum. It should also apologise for including refugees in the first place.”

In pictures: Calais crisis intensifies Show all 20 1 /20 In pictures: Calais crisis intensifies In pictures: Calais crisis intensifies Calais crisis French gendarmes try to stop migrants on the Eurotunnel site in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis French gendarmes try to stop migrants on the Eurotunnel site in Coquelles near Calais Getty Images In pictures: Calais crisis intensifies Calais crisis A migrant climbs a security fence of a Eurotunnel terminal in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis A migrant climbs a security fence of a Eurotunnel terminal in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis French gendarmes block migrants along a road to prevent them access to train tracks which lead to the Channel Tunnel in Frethun, near Calais In pictures: Calais crisis intensifies Calais crisis Policemen try to prevent migrants from reaching the Channel Tunnel operated by Eurotunnel in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis A policeman faces migrants trying to reach the Channel Tunnel operated by Eurotunnel in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis A policeman tries to stop migrants on the Eurotunnel site in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis Migrants who managed to pass the police block on the Eurotunnel site climb over a fence to make their way towards the boarding docks in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis Migrants are seen near a Channel Tunnel train in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis Migrants trying to reach the Channel Tunnel run past policemen in Coquelles near Calaisa In pictures: Calais crisis intensifies Calais crisis Migrants step over the fence as they try to catch a train to reach England, in Calais In pictures: Calais crisis intensifies Calais crisis A migrant climbs a security fence of a Eurotunnel terminal in Coquelles near Calais In pictures: Calais crisis intensifies Calais crisis Migrants warm themselves with a fire as they attempt to access the Channel Tunnel, in Calais In pictures: Calais crisis intensifies Calais crisis An Afghan flag flies above makeshift shelters at a site dubbed the "new jungle", where migrants trying to cross the Channel to reach Britain have camped out around the northern French port of Calais In pictures: Calais crisis intensifies Calais crisis Migrants build a makeshift shelter around the northern French port of Calais In pictures: Calais crisis intensifies Calais crisis Migrants build a makeshift shelter In pictures: Calais crisis intensifies Calais crisis Migrants walk in a makeshift camp in Calais In pictures: Calais crisis intensifies Calais crisis A driver climbs on his truck as he waits to cross the English channel, in Calais In pictures: Calais crisis intensifies Calais crisis Migrants walk along the roadside while a French policeman secures the area as lorries queue in Calais

The shadow Home Secretary will pledge a wholesale review of asylum policy. She will promise to change the rules so that unaccompanied children fleeing conflict would no longer be removed from Britain as soon as they turn 18 –including to countries like Afghanistan. She would also end indefinite detention in the immigration and asylum system.

The Home Office points out that asylum claims represent only a small fraction of net migration. Between April and June this year, there were 6,203 applications, up from 5,955 in the previous quarter. Some 2,360 of them were granted, down from 2,784 in the first three months of this year.

A Conservative spokesman said: “All claims for asylum are considered on their individual merits. The last Labour Government left a backlog of 450,000 asylum cases – so we’ll take no lessons from it on the best way to operate an efficient and humane asylum system. Since 2010, we have cracked down on the abuse of our asylum and immigration systems which Labour did nothing to address, making sure they work in the interest of those who play by the rules and genuinely need our help.”