There are signs the cash-for-honours affair may be nearing its climax after prosecutors said they had "all the evidence we need" to decide whether to bring charges.
The Crown Prosecution Service (CPS) asked Scotland Yard to conduct further inquiries after the original evidence file was handed over in April.
But a CPS spokeswoman has insisted: "We have all the evidence we need to make a decision. The review of the evidence is ongoing."
It emerged last week that Tony Blair had been interviewed for the third time by detectives.
The former Prime Minister - the first sitting premier questioned in a criminal inquiry - was treated as a witness each time.
Two of Mr Blair's closest aides - Labour's chief fundraiser, Lord Levy, and ex-director of government relations Ruth Turner - and millionaire party donor Sir Christopher Evans have been arrested in connection with the probe.
All three deny any wrongdoing.
PM Gordon Brown moved to distance himself from the affair on Tuesday by announcing that the Government's legal officer will no longer have the power to direct prosecutors in individual cases.
The former Attorney General, Lord Goldsmith, had sparked controversy by insisting he had a constitutional duty to be involved in deciding whether to charge colleagues.
However, the new incumbent, Baroness Scotland, will play no role in determining the matter.
