The Electoral Commission said that having reviewed "all the evidence" it had decided no further action was needed over a £1,500 gift that Ms Harman received indirectly from property developer David Abrahams.

Scotland Yard will also not be asked to investigate more than £58,000 in loans and donations totalling £6,000 which were reported to the commission late.

A spokeswoman for the commission said: "Having reviewed all the evidence the commission has decided not to refer this matter to the police."

The commission said its investigations had concluded and that two donations totalling £6,001 were reported late, as well as two loans totalling £58,000.

The £1,500 gift channelled through Mr Abrahams' employee Janet Kidd had been impermissible, and was not reported properly.

However, Ms Harman's campaign team had returned the money within the 30-days period allowed under donations rules.

The commission spokeswoman said: "We have written to Harriet Harman making clear that failure to report on time is a serious matter and we expect her to comply with the rules."