Standard Life said the majority of its long-term savings customers had seen an increase in the value of their policies during the past year, despite stock market volatility.

But the group said yesterday that not all of its with-profits customers, whose policies mature this year, would see an increase in the final bonuses they receive on their plan.

Instead, it said some customers would have higher final bonuses than were paid last year, while others would have lower ones, although it declined to say how many customers fall into each camp, or what the range of bonuses being paid is.

The group said someone who took out a 25-year endowment policy into which they paid £50 a month could expect a final payout of £29,290 if their policy matures this year.

A pensions policy into which someone paid £200 a month for 20 years will be worth £81,629.

Margaret Flaherty, who is the with-profits communications manager at Standard Life, said; "After an encouraging start to the year for investment markets - we have seen sharp falls in equity values over the last couple of months.

"We are pleased to say that, despite the recent volatility in investment returns, most with-profits investors will have seen an increase in their plan value over the last year."

With-profits are long-term savings products that aim to smooth out investment volatility by holding back some returns in good years to pay out in bad ones.

They are often taken out as a pension or an endowment to pay off a mortgage.