DONALD Trump feels "betrayed" by Alex Salmond over plans for an offshore wind farm close to his £750 million golf course development and has threatened to sue the Scottish Government if the proposals get the go-ahead.

The billionaire's comments come amid his intensifying efforts to block plans for 11 turbines 2.7 miles from his luxury leisure resort at the Menie Estate in Aberdeenshire.

Building work at the estate has been put on hold until a decision has been taken on the wind turbines, with Mr Trump claiming he would ditch his investment if the development is sanctioned.

Yesterday, he upped the ante in his campaign by claiming he had enjoyed a strong relationship with the First Minister in the past.

The tycoon said: "I feel betrayed. I had a very good relationship with Alex Salmond, and I like Alex Salmond, but I can't let a thing like this happen."

Niall Stuart, chief executive of Scottish Renewables, claimed Mr Trump was being "aggressive".

He said: "We are at a loss as to why Mr Trump has taken such an aggressive tact. There is no reason why he can't continue with his golf course and Scotland go on securing our future by building a world-class renewables sector.

"If he were genuinely concerned about Scotland he would support the renewable energy industry."

No-one from the Trump Organisation was available yesterday to clarify the basis for any legal action after Mr Trump claimed he could bring "a very large lawsuit" should the turbines be approved.

The application for an offshore energy testing station is currently being considered by Marine Scotland, with a decision likely within the next two months.

Mr Trump said: "I have been told by our attorneys, our lawyers, that we can bring a very large lawsuit and probably win the lawsuit based on the harm that these horrible things will do to Scotland.

"I've been told we have a very good lawsuit, and we can delay [the wind farms] for years to come."

The Trump Organisation has pledged a reported £10m for Communities Against Turbines Scotland (Cats) to support its lobbying against wind farms, with representatives of the tycoon due to fly into Scotland this week to meet campaigners. A site visit to the Menie Estate is also planned.

Stuart Hosie, deputy leader of the SNP's Westminster group, said he would "probably doubt" Mr Trump's lawsuit would have any traction.

He said: "There is no decision made on the deployment of the facility on the Menie Estate. That decision will be taken in due course and I'm sure it will be taken absolutely properly.

"The key thing to remember here is that this facility is a test facility. It's 11 turbines, and it's about three-and-a-half kilometres off the coast. It's not a full-scale wind-turbine array. It will be a speck in the ocean somewhere miles away."

Mr Hosie called Mr Trump "a very colourful character", adding: "If Donald Trump isn't happy I'm sure he will do whatever he feels is necessary, but so long as the planning process here is done absolutely scrupulously, as it will be, I'm not sure where Mr Trump will go with it."

Mr Trump intends to visit Scotland in the near future to give evidence at a parliamentary inquiry into the Scottish Government's renewable energy policy.

Mr Trump said he would be "honoured" to contribute to the Holyrood debate although no formal witness list has yet been drawn up.

The Scottish Government declined to comment further on Mr Trump's escalating war of words over the turbines.

Mr Salmond effectively rescued Mr Trump's golf course plan back in 2007 by "calling in" the application to the Scottish Government after it was turned down by local councillors.

However, in a letter last week, Mr Trump told the First Minister that he was "hell-bent on destroying Scotland's coastline" with wind turbines, which he described as "ugly monstrosities" and "horrendous machines".

David Rodger, spokesman for Vattenfall, the company which has proposed the Offshore Wind Deployment Centre at the heart of the row, said he saw "no reason" why the turbines couldn't exist alongside the golf course.

He said: "We do think that both projects can co-exist, with the two interests working together. The project is extremely important strategically in terms of off-shore wind.

"The project has received €40m-worth of European funding. It is very much a stepping stone for the industry. The project is very important in the current economic climate and will offer tangible benefits."

Susan Crosthwaite, chairwoman of the Cats campaign group, said Mr Trump's support had helped to "expose" the drive for off-shore wind development in Scotland.

She said: "I think a lot of people feel very betrayed by this energy policy.

"These developments are fact, not fiction, and the great thing about what Donald Trump is saying is that it brings all the information out into the open."