The Irish credit union movement is one of the most successful co-operative movements on the island, with a huge percentage of the adult population as members and enormous amounts of money on deposit. Its success is now causing it difficulties.

Central to the tension within the movement is the fact that the vast bulk of the membership belongs to the top 100 of the 536 credit unions affiliated to the Irish League of Credit Unions.

Yet when the affiliates' representatives vote at the league's annual meetings each credit union has one vote.

This means that a credit union such as the one in Tullamore, which has 25,000 members, handles thousands of transactions every week, and has the capacity to allow members use the banking system's ATMs, has as much or as little say in the movement as a credit union that has 500 members and opens on two evenings a week.

This is reflective of the movement's values and few within the movement are in favour of changing the ethos to one of "might is right".

On the other hand, however, the voting arrangement means that the vast majority of votes at any a.g.m. are held by delegates who represent only a fraction of the membership.

The issue becomes crucial when the movement is seeking to address an expensive issue such as technology. The Isis project involved an attempt to select a standard system which would link up the affiliated credit unions.

One of the costs involved would be the operation of a communications link-up between the various credit unions and a central system in Dublin. Such lines are costly and it was the league's proposal that the cost for all lines be carried in such a way that large credit unions would be subsidising small ones.

While solidarity is strong within the movement, many members felt the extent of the subsidisation involved in the Isis model just did not make business sense.

"To me, it would make more sense to see a solution for the top 150 credit unions who could accommodate it, and others could come on board when they are able," said a source.

If the credit union movement could get its technology needs solved in such a way that it was linked to the banking system, members could have their wages or their savings transferred electronically to their credit union accounts.

Also, crucially, State payments could be electronically transferred to accounts. And withdrawals could be made through the ATM system.

Following the collapse of the Isis project, a number of the larger credit unions may be making direct approaches to companies which might be in a position to supply a system.

The exact status of these approaches is not clear. At least some of the larger credit unions are known to be of the view they should wait to see what the league proposes for replacing the failed Isis project, before deciding if they should strike out on their own.

One source said he sees three broad categories of solution: a new league proposal; a proposal or proposals coming from the supplier companies; or a proposal from a group of credit unions which come together to sort out their own needs.

Another source says the danger of a split in the movement is there, but that the fault-line is not between the larger and the smaller credit unions. "It's between those who have a clear understanding as to where they want to go, and the others."

The source said it is important for the movement to remain united and that the league performs a very useful function in relation to such matters as making representations to government.

"Personally, I feel that what happens over the next 12 to 18 months will decide whether it remains united. I think it's best that it does, but we need to decide where we're going."

Interestingly, while many people would prefer to be a member of a credit union which can accommodate electronic fund transfers, credit union executives say it may not be the case that members also want the capacity to make withdrawals through ATMs. People may not want easy access to their credit unions savings.