The Dutch central bank is threatening to fine dozens of pension funds because they are not giving enough detail about the costs of their asset management, the Financieele Dagblad reports on Thursday.

The paper says over a quarter of the country’s pension funds cannot explain what the cost of investing their assets in 2012 actually was. ‘This is unacceptable,’ Olaf Sleijpen, head of the bank’s pension supervision department, told the FD.

Pension funds have been required to provide the central bank with detailed costings since 2012. The bank says it is giving the pension funds which do not meet the requirements a second chance to do so or face fines of up to €1m.

‘Pension funds need to have proper insight into the costs, otherwise they cannot decide if certain investments are desirable or not,’ Sleijpen said. The problems centre on smaller funds which have less clout to get the figures from their asset managers, he said.