Standard Life plc has reported operating profit before tax of £751m for 2013, down by 13% compared to £867m during the corresponding period last fiscal due to lower other operating income.

For the year ended on 31 December 2013, its assets under administration increased by 12% to £244.2bn, while the net inflows rose 92% to £9.6bn.

The life insurer said that its fee revenue grew by 15% to £1.45bn.

Standard Life plc CEO David Nish said the company enjoyed another strong year with business unit underlying performance up 25% to £704m.

"In the UK we are capitalising on the opportunities created by the Retail Distribution Review and auto enrolment. We attracted 340,000 new customers and increased assets by 13% to £150 billion," Nish added.

Meanwhile, Standard Life has warned that the company may relocate business elsewhere, if Scotland became independent country from the UK and the process is likely to put approximately 5,000 jobs at risk.

"We have started work to establish additional registered companies to operate outside Scotland into which we could transfer parts of our operations if it was necessary to do so," Nish added.