The Brexit campaign could lead to race relations being 'permanently' harmed in the UK, Lord Campbell has warned.

Former Liberal Democrat leader Lord Menzies Campbell made the claim as the referendum campaign intensifies in the final days.

The peer compared the pro-Leave campaign's "tactics" to that of US Republican presidential hopeful Donald Trump.

The American billionaire is proposing to build a wall between the United States and Mexico to prevent illegal immigration as well a total ban on Muslims entering the country.

Lord Campbell said: "As the Remain side, we must robustly seek to promote the benefits that migrants from other parts of the EU have brought to the UK.

"We know that they make a major contribution to the economy, as well as socially and culturally, and what we are seeing is a deliberate stoking-up of fears and prejudice in a desperate attempt to boost support for Brexit.

"There are similarities between the tactics being used by the leaders of the Brexit campaign and Republican presidential candidate Donald Trump on immigration.

He continued: "To counter this we need to go on the offensive and highlight the positive benefits that migrants bring to this country.

"The language we are hearing is extremely ugly and the danger is that race relations in this country will be permanently challenged if the positive case is not set out and the rhetoric toned down, whatever the result."

Lord Campbell's comments were dismissed as a "smear" by Scottish Vote Leave director Tom Harris.

The former Labour MP said his opponents have been complaining about the topic of immigration from the beginning of the campaign as they have "no answer" to Vote Leave's questions.

Harris said: "The Remain campaign has been complaining from the outset that immigration was even being discussed during this referendum, because they have no answer to the charge that in the EU we have no control over our borders.

"The reason immigration is being discussed is not because Vote Leave has provoked it - it's because ordinary voters demand we talk about it. They are fed up with the Remain camp lecturing us on what we can and can't discuss.

"This attempt by Lord Campbell of Pittenweem to smear Vote Leave and everyone who intends to vote Leave on June 23 should be beneath him. Once again it illustrates just how little positive Remain has to say in defence of EU membership."

Voters will go to the polls on June 23 to decide if the UK should remain or leave the European Union. It is the first referendum on Britain's membership since 1975.