Ed Miliband has attempted to clarify Labour's position on the coalition's radical pension reforms, insisting he backs looser rules.
But Mr Miliband said the party wanted to "scrutinise the detail" before committing to support the changes in Parliament.
The comments came after the Opposition was criticised for a muddled response to George Osborne's Budget proposals, which would stop pensioners being forced to buy annuities and allow them to cash in funds.
Mr Miliband did not address the plans directly in the House, and senior figures such as former frontbencher Tom Watson have raised concerns about people blowing their retirement pots.
"We're in favour of greater flexibility when it comes to pensions," Mr Miliband said in an interview.
"There are certain questions that now need to be answered by this government about the fairness of these proposals.
"Is it going to help all lower and middle income tax payers as well as those at the top of society?
"Is it going to ensure that those who want to buy an annuity - which is part of the current system - can do so, particularly if they are on low or modest income. And is the Government going to ensure that there is the right advice available to people?
"These are complex proposals. We need to scrutinise the detail and we need to have some clear answers from the Government on some of those questions."
Treasury minister Sajid Javid said: "As part of our long-term economic plan to build a more secure and resilient economy, we are making it easier for people who work hard and do the right thing to save and to have a more flexible pension.
"But, after 48 hours of having nothing to say at all, Ed Miliband has finally confirmed that Labour do not trust people who work hard to look after their pensions.
"The people who benefit most from this measure are low and middle earners who have saved throughout their lives, and yet Labour don't think they deserve the right to control their own money.
"It's the same old Labour, and they have no plan to secure Britain's future."