Dutch civil service scheme ABP could have to pay up to €1bn after discovering 16,000 participants and pensioners who were entitled to, but not receiving, additional labour disability benefits.

The pension fund said it would pay the benefits in arrears, and also compensate disabled scheme members who had continued to pay contributions despite being exempt from doing so.

Jos van Dijk, spokeswoman for the €431bn pension fund, said the discrepancy was found after comparing figures from social security insurer UWV with ABP’s own data.

“The observation by the UWV that the number of disabled people was rising was not reflected by our figures,” she said.

Although participants needed to apply for their pension themselves, ABP said everybody should receive the benefits to which they they are entitled.

“That’s why we have sent all our participants a letter explaining how they still can sort out the matter correctly,” said Van Dijk.

According to the spokeswoman, affected members missed out on €200 a month on average.

As the right to the additional labour disability benefits has existed since 2007, the total amount involved could be significant, she indicated.

“Although we need to have a second look at almost 5,000 cases, we have factored in a total amount of approximately €1bn,” Van Dijk said.

ABP said that processing the applications could take up to six months, but people who needed money sooner could receive a deposit.

The civil service scheme, which has approximately 3m participants and pensioners, said it would adjust its IT systems to improve its treatment of disability benefits.

The case is the second time this year that ABP has had to address incorrect payments to members. In March it emerged that the pension scheme had incorrectly overpaid 700 pensioners by €3m due to a data error.