The banks - which include British high street names such as Lloyds TSB and Barclays as well as leading global investment bank Merrill Lynch - have come together to form the Global 2000 Co-ordinating Group.
One source explained: "We found we were all asking the same types of questions in the same sorts of areas. This is very much an attempt to share in the effort and the costs of preparing for the year 2000."
The banks' first task will be to identify cities, countries and firms which are important to the smooth functioning of global financial markets and particularly vulnerable to the millennium bug.
Once this hit-list of potential trouble spots has been drawn up, the banks will "encourage actions" to improve year 2000 readiness.
A source denied the group was trying to be a "global policeman", but added: "It is true this is an influential group of banks. If they agree on what the problems are, they should be able to exercise influence to ensure there is a satisfactory solution".
The group said its initial information gathering exercise would assess the readiness of financial services providers, and would also cover electricity suppliers, telecoms companies and transport firms.
The group intends to invite all financial services providers to join its campaign. "There will be no limit on the number of participants in the Global 2000 Co-ordinating Group", it said in a statement. It will be run by a steering committee consisting of the founding members and at least one representative from countries that are major players in global financial markets.