Former defence secretary Gavin Williamson has described an investigation into the National Security Council leak as a "shabby and discredited witch hunt" and called for a "proper, full and impartial" investigation into it.
In a statement issued after Scotland Yard said that the Huawei leak did not amount to a criminal offence, Mr Williamson said: "With the Metropolitan Police not willing to do an criminal investigation it is clear a proper, full and impartial investigation needs to be conducted on this shabby and discredited witch hunt that has been so badly mishandled by both the Prime Minister and Mark Sedwill."
Shortly after releasing the statement, he posted a picture on Instagram of Margaret Thatcher, describing her as a prime minister who had "the courage to stand up for her values, party & country".
Earlier on Saturday, Met Police Assistant Commissioner Neil Basu said the leak of information about Chinese tech giant Huawei "did not contain information that would breach the Official Secrets Act".
Mr Basu also said the leak "did not amount to a criminal offence".
Mr Williamson was sacked by Theresa May after she said she was handed "compelling evidence" he was behind the leak - something he has denied.
Some MPs have called for Mr Williamson to be prosecuted after it was suggested he had breached the Official Secrets Act.
Others believe he should be allowed a chance to defend himself in an official investigation.
However, it now seems police will be taking no further action.
Asst Comm Basu, the head of the Met's Specialist Operations, said earlier on Saturday: "I have spoken to the Cabinet Office regarding the nature of the material that was discussed in the National Security Council.
"This material was used to inform a discussion, the outcome of which was subsequently disclosed to the media. I am satisfied that what was disclosed did not contain information that would breach the Official Secrets Act.
"I have considered all the information available to me and I have taken legal advice. I am satisfied that the disclosure did not amount to a criminal offence, either under the Official Secrets Act or Misconduct in a Public Office. No crime has been committed and this is not a matter for the police.
"Any organisation has the right to conduct an internal investigation into conduct in the workplace.
"It is not a matter for the police unless a crime is alleged. At no time have the police been provided with evidence by the Cabinet Office that a crime has been committed nor has it been suggested that a Gateway process would be required to enable that determination to be made.
"No crime has been alleged by the owner of the material and I am clear that the leak did not cause damage to the public interest at a level at which it would be necessary to engage Misconduct in a Public Office.
"It would be inappropriate to carry out a police investigation in these circumstances."
Williamson was sacked from his role as Defence Secretary following days of searching for the person who leaked information from the UK's National Security Council.
Mrs May has faced a growing backlash over her treatment of Mr Williamson, who insists he did not leak highly sensitive information about the government's 5G Huawei deal discussed during a National Security Council meeting.
But the prime minister defended her decision to sack Williamson, telling ITV Wales that she'd made the ''right decision''.