The social media firms have been accused of 'enabling criminal activity'.
Leonard Doyle, of the UN's International Organisation for Migration (IOM), said migrants were 'lured to Calais' with little oversight from tech giants.
Social media firms have introduced a measures to curb child pornography and terrorist activities. But Mr Doyle said efforts to prevent people-smuggling had been 'microscopic' by comparison.
'The guy in the village with nothing but a cracked smartphone can meet a smuggler in a heartbeat,' he said.
'This person will often have no sense that this is a trap, no sense that this is going to end up in their prostitution, their slavery, their murder, their drowning.'
The IOM says people-smuggling now represents the third largest business for international criminals.
Mr Doyle told The Independent: 'If someone does a search for child pornography, a flag that this is illegal will come up, saying... you're committing an illegal act.
But they won't do that for migration. They're enabling this criminal activity to happen.'
A spokesman for Facebook, which also owns WhatsApp, said: 'People-smuggling is illegal and any ads, posts, pages or groups that coordinate this activity are not allowed on Facebook.
'We're always improving the methods we use to identify content that breaks our policies.'
The Daily Mail
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