A Dáil debate on the proposed inquiry into incidents in the Cavan-Monaghan Garda Division has been cancelled after the Ceann Comhairle told the parties some matters were sub judice.

The debate had been due tomorrow.

The inquiry was one of the investigations ordered by the Guerin Commission prompted by allegations made by Sgt Maurice McCabe.

Its findings led to the resignation of then minister for justice Alan Shatter.

It is understood that the Ceann Comhairle's decision to block the debate is linked to a High Court action being taken by Mr Shatter challenging aspects of the Guerin Report.

It is not known if Mr Shatter was in touch with the Leinster House authorities to insist that the debate not go ahead.

Sources suggest the issue may be discussed at a meeting of the Committee on Procedure and Privileges later.

An Oireachtas spokesperson said Ceann Comhairle Seán Barrett had the power to either allow or disallow debate on a matter that is sub judice.

Having considered the text of the motion tabled, he had come to the conclusion that the motion was not in order for debate.

However, he is prepared to allow the motion to be moved without debate, as this obviates the risk of encroachment by the Dáil on the functions of the courts.

Under the Commission of Investigations legislation, establishing an inquiry must be approved by both Houses of the Oireachtas.