US private equity giant, the Blackstone Group, is facing claims that it engaged in a 'sophisticated conspiracy' to effectively oust the O'Flynn brothers from their business empire.

Lawyers for the group say the claim is groundless and the Commercial Court will decide later whether it should be struck out before a full hearing of the case in October.

In May, a Blackstone subsidiary paid €1.8bn to takeover NAMA loans connected to O'Flynn Construction.

Two months later, Cork developers Michael and John O'Flynn claim they were given just hours by that company to discharge personal loans of around €16m.

Having failed to satisfy the debts within that time, receivers and an interim examiner were appointed over O'Flynn companies.

Last month the developers scored a victory and wrested back control of the group but the legal wrangle is due to be heard in full in October.

Part of the brothers' claim is that the Blackstone entities were engaged in a 'shocking' conspiracy and that a crisis was deliberately contrived that would enable receivers to be appointed to O'Flynn companies.

The private equity group says it is an entirely unsubstantiated allegation that should be struck out. The court will decide on it later.