But in his first comments since his arrest, Jose Lopez, who was a minister under Cristina Fernandez de Kirchner, gave no further details.
The cash was found after nuns told police a man was throwing bags into their compound.
The story has enthralled Argentina, which has been gripped by several corruption scandals.
At the time of his arrest, Buenos Aires provincial security chief Cristian Ritondo said Mr Lopez "was caught red-handed with six bags, a suitcase and a weapon and he was later identified as a Public Works Minister Jose Lopez from the previous government".
Mr Lopez was found to be in a disorientated and emotional state and police have not been able to interview him since then.
He has been receiving psychiatric treatment while in prison.
Mr Lopez told the judge that when he had recovered his "psychiatric and physical strength" he would give evidence about how the millions of dollars had come to be kept in his home.
Mr Lopez is being investigated for "illegal enrichment" under the Kirchner administration.
An Argentine ex-minister has said that almost $9m (Â£6.9m) he had tried to hide in a convent had come from politics.