EU immigration drives down wages but people are afraid to discuss is for fear of accusations of racism, according to a former SNP deputy leader.

Jim Sillars warned that immigration has become a toxic subject thanks to former Tory Minister Enoch Powell.

Mr Sillars spoke in favour of leaving the European Union while the remain campaign highlighted benefits for workers form being in the EU.

Speaking at a campaign event in Edinburgh, Mr Sillars said: "The temporary economic migrant can have a depressive influence on wages in an economy where that number of economic migrants has got control.”

But he argued people have been warned off the topic for fear of negative publicity.

He added: "I think the great tragedy in the debate on immigration is that ever since Enoch Powell's rivers of blood speech away back in the 1960s, immigration has been a toxic subject which people have run away from because they are afraid that if they say anything they will be labelled as racists, bigots and xenophobes."

A former Labour UK trade minister at the same meeting said EU membership allowed some bosses to lower workers’ pay.

Nigel Griffiths, Scottish co-ordinator of the Labour Leave campaign, said: "Free movement of labour rules are allowing unscrupulous employers to import cheap foreign labour and force down UK wage rates.

"The Bank of Scotland produced a report in December saying that wage rates have been depressed by 2% as a result of that."

He said the head of the remain campaign Lord Rose admitted low skilled workers’ wages could go up if Britain left the EU.

The remain campaign however said that the EU single market supports 3million jobs, provides paid leave, parental rights, holidays and anti-discrimination laws and protects living standards avoiding potential recession.

John Edward spokesman for Scotland Stronger In Europe, John Edward launched the Guarantee card

He said: "These guarantees set out clearly the case for remaining in the European Union - including protecting our economic wellbeing and security.

"They show why Scotland will be stronger and more prosperous if we vote to remain on June 23.

“Whenever Leave campaigners are asked what the UK would look like outside the EU, all they can say is 'we just don’t know’.”