Standard Life has said it is still in the dark over "material issues" surrounding Scottish independence - six months after issuing a plea for further clarity.

The pensions and savings company, which has been based in Scotland for 189 years, said uncertainty remains for its four million customers, its shareholders and staff because of five outstanding areas of concern.

The Edinburgh-based firm highlighted in February issues such as the currency that the country would use and the shape and role of its monetary system should Scotland vote in favour of independence on September 18.

In its half-year results today, the company warned: "We do not believe that further clarity has been provided on any of these issues since our 2013 annual report and accounts was published on 27 February 2014."

Standard posted a 12% rise in half-year profits to £339 million today as it capitalised on a surge in the number of workers being auto-enrolled into company pension schemes.

Its UK business now looks after 1.5 million workplace customers and the company said it expects to add more than 300,000 in the course of this year.

The company said: "Our UK business is capitalising on being shaped and positioned to benefit from regulatory, market and demographic changes."

The company, which employs about 5,000 people in Scotland out of a total headcount of 8,500, has around £254 billion of assets under administration.

Standard Life has seen an impact on sales of its annuity products following Chancellor George Osborne's shake-up of the pensions industry, under which retirees are no longer forced to buy annuities.

The company said: "It will take some time before long-term trends become clear and, whilst a smaller proportion of our customers with small pots are still choosing to annuitise with us, many are instead choosing to defer their decisions."