Police wonder if Vaz allegation was a "tactical" move
Mr Vaz alleged that Eileen Eggington - a former senior Special Branch officer with the Metropolitan Police - had made a telephone call to his sick and elderly mother.
The standards and privileges committee also noted that the allegation led to Miss Eggington being interviewed by Leicestershire Constabulary, and that it could have intimidated her or undermined her credibility.
After Ms Filkin contacted Leicestershire police about Mr Vaz's accusation, he subsequently accused her of interfering in a criminal investigation and threatened to report her to the Speaker of the House of Commons.
'Range of offences'
"By wrongfully interfering with the House's investigative process he also committed a contempt of the House," the committee concluded.
Detective Superintendent Nick Gargan of Leicestershire Constabulary said in a letter to Ms Filkin that the force had concluded that no malicious telephone calls were made to Mr Vaz's mother.
He revealed that the force had also considered whether Mr Vaz himself had committed any offences in the course of his contact with the force.
The officer wrote: "We considered a range of possible offences, including wasteful employment of the police and an attempt to pervert the course of justice."
Mr Gargan continued: "We cannot rule out a tactical motivation for Mr Vaz's contact with Leicestershire Constabulary in this matter, but the evidence does not support further investigation of any attempt to pervert the course of justice.
"Indeed, even if we were to produce evidence that Mr Vaz was intending to undermine or destabilise witnesses, they would be witnesses before the Parliamentary Committee on Standards and Privileges rather than a court of law."
Mr Vaz said in a statement: "At the time this report was completed the police had indicated they would not be investigating this matter because of my mother's ill health.
"I can now confirm that, as of late January, the police will be investigating this matter and I believe we should suspend judgment until that investigation is complete.
"Mrs Filkin's memorandum has, therefore, been published before the full facts are known."