Senior figures in EBS have become "very concerned" at the lack of preparation by Irish Nationwide (INBS) for the proposed merger be­t­ween the two entities, sources close to the discussions say.

The mutuals have been in the due diligence and data-gathering stage of merger talks for the past few weeks, but progress has been slow because of resourcing issues at INBS, the sources said.

Poor organisation and a lack of documentation on loans and valuations was also hampering efforts to push the merger forward.

Executives are trying to consolidate enough information to determine the outline of the new entity and have not engaged in any strategic discussions or addressed the composition of a new board yet.

The sources said both sides were reasonably confident they would be ready to execute the deal after their expected post-Nama recapitalisations in late February or early March. The government is expected to have to boost the capital reserves of the two societies by €2.4bn.