Keith Cochrane, chief executive of the Weir Group, tonight joins the group of senior Scottish business figures to voice concerns about independence.

In a speech to business people and accountants, the head of the FTSE100-listed company, warns that Weir can keep its head office in Scotland only if there is certainty over its operating environment.

Mr Cochrane cites concerns over currency, taxation, and EU membership, and adds that he will personally be voting No in the referendum.

In his speech, he says: "The question I am most often asked at the moment is will the Weir Group leave Scotland in the event of a Yes vote?

"My reply is always the same, I can't answer that question without knowing the answer to simple questions like, 'what will the currency arrangements be?', 'what will the tax regime look like?', 'will Scotland remain a member of the EU?'.

"But let me take this opportunity to tell you a little more about how I am thinking, as chief executive of one of Scotland's largest companies, just a week away from the most important vote in our nation's history.

"Firstly, Weir is a proudly Scottish company but the vast majority of our business is conducted overseas. In fact, 98% of our revenues are now generated outside Scotland. We no longer have manufacturing facilities in Scotland and our three Scottish service centres will remain here as long as there are customers to serve. So from an operational perspective, any negative impacts arising from a Yes vote would be minimal.

"So that leaves our head office of around 70 people which each year contributes tens of millions of pounds to the local economy including fees for audit, due diligence and tax advice, by virtue of being based here in Glasgow."

Mr Cochrane continues: "Weir is one of a handful of Scottish based FTSE100 businesses, so I suspect the issues I have to consider are shared by my fellow chief executives. Yesterday, Standard Life reassured customers and shareholders that they had the ability to move the billions of pounds in pension funds and savings they manage to England if they felt it was necessary.

"This morning we learned that RBS and Lloyds would be moving their head offices south in the event of Scotland deciding to leave the union.

"This is not bluff. This is not bluster.This is reality, not rhetoric.Companies do not make these announcements lightly. These are the very real risks businesses now have to address and they have the potential to have serious impacts on Scotland's economy and the prosperity of her people.

"All business leaders have a fiduciary duty to do what is best for our shareholders and Weir will only continue to be based here if the business environment which has helped Weir grow into a truly global company continues to support our ambitions. That means certainty over issues like currency, certainty over issues like taxation and certainty over issues like EU membership.

"If there is a Yes vote, we need to get those answers quickly. It is simply unfair to leave businesses in the dark for many months; unable to invest in new opportunities, unable to hire new staff and perhaps ultimately unable to view Scotland as a competitive home for our businesses."

Mr Cochrane adds: "As I say, Weir is well placed to take appropriate steps, if necessary, to mitigate any negative impacts of independence.

"But on a purely personal level, I am deeply worried for my country. We are all proud Scots but we shouldn't be seduced by sound-bites alone. Scotland is a country built on reason: a place which traditionally favours substance over style. I have spent my entire working life building businesses in and from Scotland. It is a great place to succeed and being an integral part of the UK is an important part of that.

"If we vote Yes next week, we will walk away from the most successful economic union the world has ever seen. We will be rejecting an arrangement which supports one million jobs and we will be doing it for what? A 3% cut in corporation tax which only a minority of firms pay and which would be at the cost of losing the UK tax base.

"That doesn't sound like a good deal for Scots and it doesn't sound like a good deal for Scotland. These are the reasons I will be voting No next Thursday."