The government had not responded to weekend media reports that the formulation of such a motion was underway.
Speaking to BBC Sandeshaya, Senaratne said the only way out was to move a no-confidence motion if the judge in question did not resign.
There have been reports that one judge faces charges of assault of a woman domestic help, while another is alleged to be having a legal consultancy service run by her husband.
War crimes probe
When asked if a reliable local investigation could be expected from a judicial system comprising judges with questionable reputation, the spokesman said the government would choose the best judges.
We will not deceive the world community, and we will obtain advice and technical assistance from them, he said, adding that internationally-recognized judges like Weeramantry would be brought for an honest investigation.
Both Sinhala and Tamil extremists were against the proposal for such an investigation, he added.
