UK Foreign Secretary Philip Hammond says millions of “marauding” migrants pose a threat Europe’s standard of living and social structure and must be sent back home.

Hammond made the comments to the British state-funded BBC on Sunday while on an official visit to Singapore.

According to Hammond, “the gap in standards of living between Europe and Africa means there will always be millions of Africans with the economic motivation to try to get to Europe.”

He said the current laws in the European Union meant that migrants could be “pretty confident” that after setting foot on EU soil they would not be returned to their country of origin.

“So long as there are large numbers of pretty desperate migrants marauding around the area, there always will be a threat to the tunnel security. We’ve got to resolve this problem ultimately by being able to return those who are not entitled to claim asylum back to their countries of origin,” he said. “Now that is not a sustainable situation because Europe can’t protect itself, preserve its standard of living and social infrastructure if it has to absorb millions of migrants from Africa.”

Hammond also talked about migrants coming into the UK and other parts of Europe from Syria, battered by a foreign-back crisis since 2011.

"We need responsibility and international leadership from this government, not scaremongering," he said. "Those fleeing Syria are desperate refugees from a country being torn apart by war."

Hammond made the comments as 117 suspected "illegal immigrants" were found in a single "suspicious" lorry while traveling from one point to another in the United Kingdom.

His comments followed criticism of the UK by a United Nation’s special rapporteur on the human rights, who said that Britain's approach to the "courageous" migrants at Calais is tantamount to "racism".

Last month, almost 50,000 migrants arrived in the EU through Greece alone, according to the latest figures from Frontex, the EU border agency.