The letter on the subject was sent to Michel Barnier, European commissioner for internal market and services. It called for the commission to expand the scope of its proposed stipulations in terms of the open access requirements that will be made of services providers in the industry.

There are concerns that companies making use of derivatives traded on exchanges or via similar facilities will engage less frequently with banking groups but will eventually find cause for concern that competition in the market for post-trade services is not as tough as it ought to be.

"The organised trading facilities or exchanges are for a significant part of the market vertically integrated with a clearing house and do not allow access to competition from other clearers," O'Donovan said.