The Edinburgh-based pensions and savings firm Standard Life has drawn up contingency plans to quit Scotland if it becomes an independent country.

Standard Life, which has nearly 4 million customers in the UK and 5,000 employees in Scotland, said it would take "whatever action necessary" to protect its business, including moving its operations to England. Gerry Grimstone, the firm's chairman, said: "We have been based in Scotland for 189 years and we are very proud of our heritage. Scotland has been a good place from which to run our business and to compete around the world.

"We very much hope that this can continue. But if anything were to threaten this, we will take whatever action we consider necessary – including transferring parts of our operations from Scotland – in order to ensure continuity and to protect the interests of our stakeholders."

Standard Life's chief executive David Nish said the company had started to register companies in England, but declined to say where Standard Life's new headquarters could be.

The financial services firm, which has £247bn under management, highlighted uncertainties over Scotland's currency, the shape of its monetary system, financial services regulation and taxes.

It also raised questions about whether an independent Scotland would be able to join the European Union by the Scottish government's preferred March 2016 target date.

Nish said these were "the fundamental things we need clarity on to evaluate the decision we are making".

Alex Salmond, Scotland's first minister, has said Scotland would continue to use the pound without the agreement of Westminster, after chancellor George Osborne along with Labour's Ed Balls ruled out ruled out currency union with Scotland.

Critics argue that Salmond's 'sterlingisation' proposal, the Panama option, would spell disaster for Scotland's financial services industry, leaving it without a lender of last resort or central bank.

Nish said people could draw their own conclusions about whether using the pound unilaterally was compatible with a large financial services industry. "We have to take into account the needs of our customers and we will begin to take actions to make sure we fulfill our actions to them."

The warning comes days after a survey revealed that two-thirds of FTSE 100 chairman who participated in a survey said they were against Scottish independence.

On Wednesday, one of Scotland's biggest companies, engineering group Weir, said it had commissioned a report into the implications of Scottish independence on businesses after warning that "very serious questions" need to be answered. The Glasgow-based company, which employs about 14,000 people in more than 70 countries, said that business must have a voice in the debate alongside the political rhetoric of the yes and no camps.

Keith Cochrane, Weir's chief executive, said the company would publicise the findings of its report, which will consider currency, pensions, trade and taxation, by early April.

He said: "This is a big issue, the debate needs to be focused on objective facts. Alongside other voters, I will personally be able to participate on 18 September, but I think it's really important that business contributes to that debate."

Although Scottish companies have been wary of entering the independence debate, Weir was among the first to raise concerns about going it alone in 2012, when Cochrane warned that talk of secession was creating uncertainty for businesses. More companies have broken cover since, with BP's chief executive, Bob Dudley, entering the debate earlier this month.

Dudley, who oversees a major player in the North Sea oil and gas industry, said he did not want to see Scotland "drifting away" from the UK. He said BP would almost certainly face higher costs due to uncertainty over the currency, which would endanger investment. Dudley spoke out after an intervention by George Osborne, when the chancellor said a currency union based on the pound would be "unworkable" in the wake of analysis by the Bank of England.