UK - Lars Rohde, chief executive at the giant Danish pensions provider ATP, has expressed concerns over the long-term impact of opt-out provisions in the UK auto-enrolment law.

Speaking in London at an event organised by Now: Pensions, ATP's UK pensions operation, Rohde said allowing people to opt-out of the new "savings-based" system would complicate the provision of pensions for them from the tax and benefits system.

He pointed out that, in Denmark, there people were left uncovered by the labour market and corporate pensions systems who would expect additional pensions to the state provision.

"Denmark is some years ahead of the UK in having this problem," he said.

He said he saw dangers in trying to run a savings-based pensions system in such conditions, adding that it may be possible to fool some of the people some of the time, but "not all of the people all of the time".

Rohde also said that concerns about the UK's opt-out provisions had been among the reasons why ATP pulled out of the bid to run the National Employment Savings Trust (NEST) system.

"But we learned a lot from the process, encouraging us to set up Now: Pensions," he added.

Looking at an investment climate with limited prospects for returns, he said people would have to save more for their pensions.

"I have a simple calculation - if you save 20% of your pay for 40 years at nil real investment return, you will have a pension sum of 800% of pay, equivalent to a 40% payout over 20 years," he said.

Rohde, who leaves ATP to become governor of Denmark's central bank on 1 February 2013, sees action on pensions as a major part of the solution to the European debt crisis.

He advises reform to public pensions, an increase in pension age and a short-term stimulus to economies.