The abortive cash-for-honours probe cost police nearly £1.4 million, it has been disclosed.
Scotland Yard incurred the bill during a 19-month investigation which blighted the final stages of Tony Blair's premiership but eventually resulted in no charges.
The figure, which was released to the Press Association under freedom of information laws, is higher than had been expected.
The CPS disclosed last month that it had spent £122,000 on advice from independent counsel before deciding to drop the case.
Staff costs made up £1,304,549 of the total £1,396,091 bill.
The Met refused to provide a breakdown of the remaining £91,542.
Assistant Commissioner John Yates, who led the inquiry, mounted a staunch defence of its conduct when he gave evidence to MPs last month.
He told the Public Administration Committee that his team found evidence that suggested there might have been "something there".
Mr Yates also indicated that some figures embroiled in the cash-for-honours controversy failed to co-operate fully - although he declined to identify them.
Four people - including some of Mr Blair's closest aides - were arrested during the probe, which began in March last year. Dozens of others were interviewed.
