Tony Blair has refused to comment on the attorney general's role in deciding whether anyone is charged as a result of the cash-for-peerages inquiry.
Mr Blair said it would not be appropriate to comment
Lord Goldsmith, a Labour supporter who attends Cabinet meetings, has refused to rule out a role in deciding whether his political colleagues face charges.
The prime minister said it was not appropriate to comment on the case.
But the BBC has learnt the Lord Chancellor said in April Lord Goldsmith would not interfere in any decision.
Lord Falconer told the Commons constitutional affairs committee in April: "It is a matter for the [Director of Public Prosecutions] and the Crown Prosecution Service to make decisions in relation to this in the normal way and, of course, the attorney general would not interfere in the normal course of decisions being made."
However, over the last few days, Lord Goldsmith has refused to rule himself out of any involvement in any cash-for-honours prosecution decisions, but has said he will act "in the interests of justice".
In a statement from his office on Monday, he said: "I understand what the Lord Chancellor was saying was the decision will be taken in the normal way, as DPP Ken Macdonald and the former Attorney General Lord Morris have made clear today, which includes consultation with the attorney general in serious and complex cases and formal consent where consent is required."
Opposition parties have complained that Lord Goldsmith is too closely linked to the prime minister and the government to be involved in this case.
The Scotland Yard investigation is looking into whether peerages or other honours were offered in exchange for money, after it was revealed that all three main parties were given secret loans ahead of the last election. All involved have denied any wrong-doing.
But Andrew Tyrie, the Conservative MP who questioned Lord Falconer in April, said he had received a "complete assurance" that Lord Goldsmith would not be involved.
He added: "How can the public have any confidence at all in the attorney general's decision on whether to prosecute the prime minister, when it was the prime minister who appointed him to his job? It is absurd."
Lord Goldsmith has promised to put the interests of justice first
Mr Blair told his monthly news conference on Monday that he would not comment on Lord Goldsmith's role.
He added: "The reason is because I don't think it is appropriate for me to say anything on this and I don't intend to."
Meanwhile Director of Public Prosecutions Ken MacDonald has denied reports in the Evening Standard that he will resign if Lord Goldsmith blocks any charges.
Mr MacDonald, a former colleague of the prime minister's wife Cherie Blair, has already removed himself from handling the case.
Lord Morris of Aberavon QC, who was attorney general in the late 1990s, defended Lord Goldsmith's right to be involved in any decisions on the case.
He added: "He and he alone is answerable to Parliament and there should be no question of this, or any other attorney general, stepping aside."