Standard Life has added its voice to growing calls for workers to be auto-enrolled into individual savings accounts (ISAs).

The insurer also called for the automatic escalation of pension contributions, in which employees' contribution rates are increased by 0.5% every time they get a pay rise.

In its report, Keep on Nudging, Standard Life suggests enrolling staff into an ISA and a pension at the same time.

However, it does predict this would have a negative impact on savers then choosing to opt-out of the system.

It predicts enrolment into ISAs would cause 3% more workers to opt out of saving, whilst auto-escalation would cause a 4% increase in opt-outs.

Under the current reforms - without the additional changes it suggests - Standard Life said it expects 82% of employees to remain in auto-enrolment.

As part of the its report, the provider also called for the government to send everyone a letter on their 30th birthday as standard, informing them of their options to start saving for retirement.

David Nish, chief executive of Standard Life, said: "Standard Life fully supports auto-enrolment into workplace pensions, which we believe offers a unique opportunity to put in place an affordable and sustainable pension system for millions of people working in the UK.

"We believe auto-enrolment can help re-introduce a savings culture in the UK and be an important first step in bridging the savings gap."

Ros Altmann, director general of Saga, has previously called for ISAs to be provided as part of auto-enrolment savings vehicles.

Auto-enrolment by numbers

What Standard Life believes the impact auto-enrolment will have on the UK savings market...

£12.5bn

The amount Standard Life says auto-enrolment could bring in to annual retirement savings by 2017, when all employers must comply.

600,000,000

The number of extra people who will be saving into pensions by the time the reforms are complete.

48%

The percentage of employees who told Standard Life they would find it easy to save an extra £50 per month.

£14bn

The increase in employer contributions Standard Life says its two extensions, auto-escalation or ISA enrolment, could bring in by 2025.

31%

The proportion of employees already in company pensions who are willing to pay more than the basic 4% of salary into their pensions, and who would increase their contributions in line with pay rises.