Alex Salmond has attacked Donald Trump over his calls for Muslims to be barred from entering the US.

In an interview to be broadcast today, the Scottish National Party foreign affairs spokesman accused the property tycoon and reality TV star of having lost the plot early in this political career.

He told Russia Today TV's Going Underground: "Most presidents of the United States or UK prime ministers usually have about 10 years in office before they go crazy. Donald Trump has made it as a candidate."

The two men have been at loggerheads since 2011 over plans for offshore wind turbines near the businessman's golf resort in Aberdeenshire.

When Trump failed to have the turbines decision overturned in the Court of Session, Mr Salmond labelled him "a beaten man who could not accept defeat".

Mr Trump responded then: "Alex Salmond ... is abusing his power by having these wind turbines littering Scotland."

The comments by Mr Salmond came as an online petition to ban the US presidential hopeful, which has become the most popular ever on the Government's website, passed the half a million mark.

The poll on the parliamentary website calling for his exclusion from the UK raced past the 100,000-signature threshold to be considered for debate in Parliament and has topped the previous record of 446,482.

At its peak, the petition was lengthening by more than seven signatures a second and users experienced difficulties accessing the page due to higher than usual traffic. It gained around 140,000 signatures in just over a day, to reach the 500,000 mark in the early hours of Friday.

The previous top spot was held by a petition earlier this year calling for the UK to accept more asylum seekers and increase refugee support, which was signed 446,924 times.

Prime Minister David Cameron said Mr Trump's comments were "divisive, unhelpful and quite simply wrong", while London mayor Boris Johnson said they rendered him "unfit to hold the office of the president of the United States".

The businessman, who owns two golf courses in Scotland - Trump International Golf Links in Aberdeenshire and Trump Turnberry in South Ayrshire - has been stripped of an honorary degree from Robert Gordon University in Aberdeen and had his membership of the GlobalScot business network removed.

But he received support from TV personality and MailOnline columnist Katie Hopkins, who urged the public not to demonise him.

Ukip leader Nigel Farage said people had "overreacted" to Mr Trump's comments and he should not be barred, even though he had "gone for a proposal that is over the top".

Mr Farage said: "Do I think people have overreacted? Yes, I do think people have overreacted, which does not mean I support the tone of everything Donald Trump has said, because I don't."

In a further comment on Twitter, Mr Trump claimed that "in Britain, more Muslims join Isis than join the British Army".

The tweet linked to an article in National Review headlined Dispelling The 'Few Extremists' Myth - The Muslim World Is Overcome With Hate, which cited a Times report from 2014 on numbers of British Muslims travelling to Syria and Iraq to wage jihad.

In the US, the Trump backlash continued as Democratic front-runner Hillary Clinton said the Republican candidate, often the butt of jokes by US commentators and comedians, had crossed a mark, declaring: "I no longer think he's funny."

"Now he has gone way over the line," said Clinton on NBC's Late Night with Seth Meyers. "What he's saying now is not only shameful and wrong, it is dangerous," she said, citing the effect his comments may have on would-be jihadists.

"This latest demand that we not let Muslims into our country really plays into the hands of terrorists, and I don't say that lightly," said Clinton, calling his comments a potential "propaganda tool."