Prime minister Theresa May’s deputy, Damian Green, is to be investigated following an allegation of inappropriate behaviour.
Activist Kate Maltby wrote in The Times that he “fleetingly” touched her knee in a pub in 2015, and this year sent her a “suggestive” text message after she posed in a corset for the paper.
The Cabinet Secretary is to consider whether he broke the ministerial code.
Mr Green has described the claims as “absolutely and completely untrue”.
Ms Maltby, a writer and academic some 30 years younger than Mr Green, said the encounters left her feeling “awkward, embarrassed and professionally compromised”.
Mr Green, the first secretary of state, and Theresa May’s effective deputy, said he had known Ms Maltby since 2014 and the pair “had a drink as friends twice-yearly”. He denied putting his hand on her knee.
“The text I sent after she appeared in a newspaper article was sent in that spirit – as two friends agreeing to meet for a regular catch up – and nothing more,” he said.
“This untrue allegation has come as a complete shock and is deeply hurtful, especially from someone I considered a personal friend.”
It comes as allegations and rumours relating to sexual harassment and abuse by MPs swirl around Westminster.