THERESA May will try to persuade Donald Trump to abandon his new tariffs that threaten a trade war as her Scottish Conservative colleagues approached Brussels over fears that tit-for-tat action could hit the scotch whisky industry.

At the start of the G7 summit in Canada on Friday, the Prime Minister will join leaders from Germany, France, Italy, Japan and the host country in confronting the US President over the imposition of tariffs on steel and aluminium.

The two-day gathering in Charlevoix, Quebec, follows a stormy meeting of the countries' finance ministers earlier this month when America was left isolated.

French finance minister Bruno Le Maire described the situation as more of a "G6 plus one than a G7" because of the rift caused by the refusal to exempt allies of the US from the 25 per cent tariff on steel imports and the 10 per cent duty on aluminium.

The European Commission has confirmed it intends to hit back with retaliatory tariffs from July on US imports ranging from jeans to bourbon whiskey.

However, Scottish Tory MPs have been alarmed at such a prospect because they fear that any tariff hike on bourbon could lead to the US retaliating with fresh duties on scotch whisky. They have written to Brussels to express their concerns of the harm tit-for-tat retaliation could have on the industry.

Last year, the US was the largest export destination for scotch whisky in 2017, accounting for £922 million in exports.

The industry is concerned about the damage potential tariffs would cause. It supports more than 40,000 jobs across the UK, including 7,000 being in rural Scotland.

Douglas Ross, the Scottish Conservative MP, who has 40 per cent of all scotch whisky distilleries in his Moray constituency, said: “There is much to celebrate in the industry just now, with significant investment, but the EU could jeopardise the success of scotch whisky with their proposal.

“I’m extremely concerned about the possibility of the EU including bourbon in the countermeasures against the United States as any American retaliation would hit jobs across Scotland that rely on our booming whisky industry.

“My Scottish Conservative colleagues and I will be doing our upmost to stop the inclusion of bourbon in retaliation plans by the EU,” he added.

On Monday in a phone-call, Mrs May told Mr Trump the US decision to apply tariffs to EU steel and aluminium imports was "unjustified and deeply disappointing" and promised to raise the issue with him at the G7 summit.

The US is also at odds with the EU nations over the Iran nuclear deal and the Paris climate change accord, both of which Mr Trump has pulled out of.

On Wednesday, German chancellor Angela Merkel predicted difficult talks at the G7 summit as a result of the US actions.

"It is apparent that we have a serious problem with multilateral agreements here, and so there will be contentious discussions," she said.

The tensions caused by Mr Trump's US administration risk overshadowing the agenda pushed by Canadian Prime Minister Justin Trudeau, who wants the summit to focus on themes including gender equality, cleaning up the oceans and creating fairer economic growth.