The new IP network, which will help slash the three-day cycle for clearing payments, was due to be ratified by the Bacs board at the end of last month.
Part of a four-year IT shake-up worth £60m, the network will allow member banks to develop a next-day service for processing direct debits and credits.
The network is due to be rolled out in the first quarter of 2002 and banks should have new payment engines for enhanced payment services by 2003.
With the Bacs network handling more than 10 million direct debits and credits every day, it is vital that the security system is watertight. However, Bacs has still to agree a common security protocol with member banks for the payments processing network.
A spokeswoman for Bacs said, "Security is a sticking point. There is no agreement as to what standard we are going for and there is no firm date for an announcement. It is taking a little longer, but we are still very keen for progress to be made this year."