Aegon is blocking customers from accessing the pension freedoms unless they take financial advice.
The Telegraph reports that those who do not wish to take advice are being given three options: cash in their entire pension pot, buy an annuity or transfer to another provider.
Aegon expects to offer the freedoms to those who do not take advice from April 2016.
An Aegon spokesman says: “Pensions can be complex and require customers to make decisions about investments, how much income to take and how long their savings might need to last.
“We are still working through our offer and will launch when we are confident it will meet customer needs.”
Pensions minister Ros Altmann says: “People who really do need to take their money should not be denied the chance unfairly. The real problem is the difficulty and large cost they face if they transfer to another provider.
“We are looking at this in our consultation and investigations and we want members of the public who are experiencing difficulties in this regard to let us know what is happening.”
Friends Life is unable to offer the pension freedoms after failing to adapt its systems.
The Government has mandated that savers with safeguarded benefits worth more than £30,000 get regulated advice before taking their pot as cash.