The loss of its State bank status could cost ACC Bank €45 million (£35.4 million) in business with the Courts Service.

ACC is one of a number of banks that manage the €750 million held in trust by the Courts Service which manages the court system. However, the imminent takeover of ACC by the Dutch group Rabobank will prevent ACC offering a particular investment product - State-backed commercial paper - to the Courts Service.

Commercial paper is an unsecured short-term promise to repay a fixed amount on a certain future date. It usually pays a higher rate of interest than normal deposits and the bank that issues the commercial paper does not give any security and the investors rely instead on the bank's credit rating.

ACC Commercial Paper was attractive to the Courts Service because it was effectively guaranteed by the Government, which owned the bank. A spokesman for ACC said yesterday that the bank planned to meet the Courts Service shortly to discuss alternative investment.

The Courts Service is in the process of appointing a number of fund managers to look after the cash it holds, most of which is held for wards of court or minors.

Rabobank is one of the top 40 banks in the world in terms of the capital underpinning its balance sheet. It agreed to buy ACC last December for €165 million.