Alex Salmond has denounced Donald Trump for racism, religious bigotry and hate preaching – and backed the campaign to ban him from Britain.

In an exclusive interview with the Sunday Herald, the SNP MP and former First Minister revealed he has signed the parliamentary petition to prevent the would-be US president from setting foot in the UK. To date well over half a million people have put their names to the petition.

Salmond’s predecessor, the former Labour First Minister, Jack McConnell, has also backed Nicola Sturgeon’s decision last week to strip Trump of his status as a “Globalscot”. It was McConnell who offered him that role in 2006.

Trump, a billionaire property tycoon based in New York, is the frontrunner to be the Republican Party’s candidate for US president. His suggestion last week that there should be “a total and complete shutdown” on Muslims entering the US provoked global outrage, following earlier rows over his attitude towards Mexicans, women and the disabled.

Salmond, when he was First Minister in 2007, supported Trump’s controversial golf resort at Menie on the Aberdeenshire coast. But the two men later spectacularly fell out, after Trump objected to wind turbines being given the go-ahead off the coast by his golf course.

Trump has gone to court to try and block the wind project accusing Salmond of being biased in favour of it. His case has been rejected by two Scottish courts, and a judgement on Trump’s latest appeal to the UK supreme court is expected this week.

Trump’s remarks about Muslims and Mexicans meant that the UK government should ban him from the country, Salmond told the Sunday Herald. “His remarks against Mexicans were most certainly racist,” he said.

On the Mulim comments, Salmond said: “The definition of religious bigotry is if you ban a whole section of people according to their religion, as opposed to what they personally have done or not done. That is most certainly bigotry.”

Salmond described Trump’s comments as “hate preaching” that would be likely to incite public disorder in the UK. He pointed out that UK ministers had previously banned the French comedian, Dieudonné M’bala M’bala, and the US shock jock, Michael Savage, for their racial and religious comments.

Trump’s remarks were similarly offensive, and likely to contribute to “attacks on people based on their ethnicity or religion,” Salmond argued. “So I think that in terms of consistency they should be considering banning Mr Trump from the country.”

A ban would also make clear to the US that most people in the UK regard Trump’s comments as “unacceptable and dangerous”, he said. It was “ludicrous” to argue, as some had, that the UK couldn’t ban a presidential candidate.

There was also a logic to banning Trump, Salmond contended. “Trump has been saying that other people should be banned from going to America. So he can hardly complain if he was banned from coming here.”

The former First Minister defended his decision to back Trump’s golf development in 2007 on the grounds that he couldn’t have anticipated what the tycoon’s attitude to wind turbines would be in 2012, or to Muslims and Mexicans in 2015. “I think it would have taken a great deal of foresight which I’m afraid is not given to earthly beings,” he said.

“I regret Trump’s behaviour, but I don’t think you can give yourself the 100 per cent foresight that would have been required. So I’ve not criticised Jack McConnell for his behaviour, because he, like me, wouldn’t have been in a position to anticipate what Mr Trump was going to do some years later.”

He insisted it wasn’t obvious at the time what kind of man Trump was, and that his views had come to light as a result of his ambition to be president. “The idea of Trump as a presidential candidate would have been something that in 2007 would have appeared far-fetched,” Salmond said.

McConnell, now Lord McConnell of Glenscorrodale, said that he fully supported the decision by the current First Minister Nicola Sturgeon to remove Trump from the Globalscot list of business luminaries. “It would be wrong to have anyone serving as a Global Scot who might discriminate when asked for advice,” McConnell said. “The First Minister was right to take this action.”

McConnell’s invitation to Trump to become a Globalscot in 2006 has been released under freedom of information law. “You have already been an outstanding spokesperson for Scotland,” the then First Minister wrote. “Globalscot would present an opportunity to do more of that.”

As well as developing the golf resort in Aberdeenshire, Trump has also bought and is redeveloping the famed golf course at Turnberry on the Ayrshire coast. He has often talked about his Scottish roots, pointing out that his mother, Mary Anne Macleod, was born near Stornoway on the island of Lewis.

But now, it seems, Scotland is rejecting him. As well as being dropped as a Globalscot, Robert Gordon University in Aberdeen last week withdrew the honorary degree it gave him in 2010 “in recognition of his achievements as an entrepreneur and businessman.”

The Green MSP and party co-convenor, Patrick Harvie, branded Trump as “increasingly fascist” and a “bigoted blowhard”. He said: “I can't imagine any self-respecting person wanting to spend money in his hotels and at his golf courses.”

The UK parliamentary petition to ban Trump from the UK has been gathering signatures at a rate of up to seven a second since it was launched on December 8. It has been signed by nearly 550,000 people.

The woman who started the petition was Suzanne Kelly, a 54-year-old journalist and activist who was born in New York and has lived in Aberdeen since 2003. She was also behind another petition that helped persuade Robert Gordon to cancel Trump’s degree.

She pointed out that she had submitted the petition before Trump suggested banning Muslims for the US. It was an earlier speech in which he appeared to mock a disabled reporter that finally convinced her that something had to be done.

“That was the last straw,” she said. “The idea had been sitting in my head for a couple of months.” As well as receiving praise from around the world, she said that she and the independent online journal for which she writes, Aberdeen Voice, received dozens of abusive emails last week.

The UK parliament is bound to consider the petition for debate, and the Westminster government will have to respond. But indications so far suggest that ministers are unlikely to agree a ban on Trump.

In an article last week, Trump hit back at his critics. “I have done so much for Scotland,” he said. “The UK politicians should be thanking me instead of pandering to political correctness.”

He said that Sturgeon and the Robert Gordon University should have told him of their plans to disavow him before he made his £200 million investment in Scotland. “I only said what needed to be said, and when I am elected no one will be tougher or smarter than me,” he added.

“I will work very hard and effectively to defeat terrorism. I have respect for the Muslim people and have great friendships with many Muslims, some of whom I do business with, but they themselves admit there is a major problem with radicalisation.”

But Trump was accused of “preying on people’s fears” by one of his arch-critics, the Scottish documentary filmmaker, Anthony Baxter, who has made two films about Trump. “While making my films I witnessed at first hand how Donald Trump bullies people in an attempt to get his own way,” he said.

“What we are witnessing now as he throws more fuel on the fire in his bid for the White House, is the same thing but on a much bigger scale - where Mr Trump is playing an increasingly dangerous game.”