Following four months of testing, the bank plans to go live with the system shortly.
Unity rejected the traditional anti-money laundering systems used by the larger banks in favour of a package from SAS. It said the software is flexible enough to adapt to the unusual behaviour of its customer base.
"We deal a lot with charities and trade unions who have thousands of transactions coming through the network. They put one large payment out into the market at the end of the day," said Neil Hartley, head of internal audit and compliance.
Although this is normal for charities and unions, most anti-money laundering packages would view the transactions as highly suspicious.
The SAS software, which runs on a standalone PC supporting an SAS datawarehouse, monitors customer behaviour over a period of time, rather than attempting to spot one-off suspicious transactions.
It uses a set of 30 customisable rules to identify patterns of money laundering and produces a monthly analysis of the bank's most suspicious customers, which staff use as a basis for further investigation.
"It really shows suspicious behaviour rather than suspicious transactions, which helps us concentrate our resources on investigation and action, rather than trying to detect money laundering," said Hartley.
All banks are required to pass details of suspicious activity to the National Criminal Intelligence Serv-ice. The Financial Services Authority (FSA) also rates banks according to their money laundering risk. Charities are known conduits for money laundering.
"The package will help us demonstrate to the FSA that we are competent and that we know what we are doing," said Hartley.
Until now the bank has relied on staff making SQL database enquiries to identify suspicious transactions.