Speaking on ITV's Peston on Sunday the Health Secretary Jeremy Hunt said that his cabinet colleague, the MP for Wyre Forest, will be investigated to determine whether he broke ministerial rules.
The claims against Mr Garnier were reported by the Mail on Sunday. The report quoted the 53-year-old as saying he did not deny the claims.
However, Mr Hunt suggested the minister may not have broken the ministerial code.
ITV News Central has tried to contact Mr Garnier to discuss the claims.
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The defendant would have been just 13 at the time of the killing