INSURANCE group Prudential is "working hard" to adapt its pension products to the government's surprise rule change, and has assured customers and staff that it will keep doing business in Scotland whatever the outcome of next month's referendum.

Prudential said its retirement annuity sales dropped 43 per cent in the first six months of the year after the Chancellor George Osborne unveiled plans in March to remove the need to buy an annuity. This has prompted some savers to defer retirement until the new rules are clear.

"We are working hard on developing new products to allow customers to take full advantage of this new flexibility," said chief executive Tidjane Thiam.

The London-listed firm, which beat forecasts with a 17 per cent rise in underlying half-year earnings, said it had delivered an "outstanding performance" in spite of the pension overhaul and uncertainty in parts of its Asian business.

Mr Thiam told reporters yesterday that Prudential "will always look after our customers and staff whatever the outcome" of the Scottish independence vote.

"Of course, as a manager I will manage the consequences of that. We will continue to operate whatever happens... we will fulfil our obligations," he added.

Prudential has about 1,300 employees in Scotland, most of whom are based at its offices in Craigforth, near Stirling.

The company reported an operating profit of £1.5 billion for the first six months of the year, up by an underlying 17 per cent, though the strength of sterling against other currencies brought the pace of growth down to seven per cent.

The UK life insurance business generated a 10 per cent rise in operating profit to £374 million, as the drop in annuities sales to £63m was counteracted by £104m of bulk annuity deals, which transfer the risk of a defined benefit pension scheme from a company to the insurer.

Asian life insurance, which represents almost a third of group earnings, brought in operating profits of £483m, a rise of 19 per cent. This growth falls to just two per cent including the effects of foreign exchange movements.

"We faced some challenges with significant and sudden depreciation of the currencies in some of our 'sweet spot' markets," said Mr Thiam.

The firm has taken on more sales agents to propel growth in the Asian regions it has deemed "sweet spots", where it views the emerging middle classes as under-insured, but said yesterday that political uncertainty including the disputed presidential election in Indonesia pose a risk.

Mr Thiam admitted he was "still animated" about his company's failed attempt to take over the Asian insurer AIA in 2010.

When asked about Prudential's interest in pursuing takeovers, he said the deal, worth almost £25bn at the time, had represented a one-off opportunity for Prudential to cement its position in Asia.

In the US, where Prudential is trying to attract some of America's 77m baby boomers as they approach retirement, the company posted a 28 per cent rise in profits to £686m. This rise is reduced to 18 per cent by currency changes.

The group's M&G asset management unit attracted £3.8bn in net new funds from retail investors in the period, while institutions added a net £427m.

The unit now manages £253.7bn and delivered a 10 per cent rise in underlying half-year profit to £214m.

"Its strategy is bearing fruit in each of its geographies, in particular Asia and the US," said Richard Hunter, head of equities at Hargreaves Lansdown. "There is little doubt that Prudential has shown again that it is a company which is firing on all cylinders."

The group increased its interim dividend by 15 per cent to 11.19p.

Shares in Prudential rose 29.5p to 1,368.5p, making it one of the biggest risers on the FTSE 100.