Inquiry into cabinet minister is understood to be examining whether he briefed newspaper against Kate Maltby

Kate Maltby, the Conservative activist who has made allegations of sexual harassment against the first secretary of state, Damian Green, received a series of “violent threats” after the Daily Mail published an article calling her “one very pushy lady”, her friends say.

With a Cabinet Office inquiry into Green’s case understood to be examining whether he played a role in briefing the newspaper against Maltby, her allies say the critical piece coincided with a flurry of threats against her, some of which she is in the process of reporting to police.

The Mail article quoted a Tory source dismissing Maltby as a “political groupie”, and another saying: “She might be more careful the next time she’s asked to write a piece trashing a decent man.”

Some at Westminster believe the piece and similar articles may have deterred other potential victims of harassment from coming forward. Maltby’s friends say she received threats on social media and by email.

Green declined to comment, but allies vehemently insisted that neither he nor any of his advisers had played any role in influencing the Mail article.

Green, who was a friend of Theresa May’s when the pair attended Oxford University together, has continued in his post while the Cabinet Office head of ethics, Sue Gray, examines his case.

The Labour MP Jess Phillips, who has campaigned against sexual harassment, said: “If it is found that Green or his people had anything to do with the Mail hatchet job on Kate Maltby in order to put off other women coming forward, the prime minister must sack him or eat every single word she has ever said about violence against women.”

The alleged threats against Maltby come amid growing concern at Westminster about the climate of political debate, with female MPs in particular reporting frequent threats and personal insults.

The prime minister this weekend condemned violent language used to attack Conservative MPs who rebelled against the government on the EU withdrawal bill last week, which some of the rebels also blamed on hostile press coverage, including in the Mail and Daily Telegraph.

After the Mail described the rebels as “self-consumed malcontents”, who had “betrayed their leader, party and 17.4 million Brexit voters”, Dominic Grieve, who tabled the key amendment, as well as his fellow rebel Anna Soubry, said they had received personal threats.

May tweeted on Saturday:

Theresa May (@theresa_may) Threats of violence and intimidation are unacceptable and have no place in our politics. Everybody should be treated with tolerance, decency and respect.

Green’s fate is likely to be announced this week, though he could then face a separate investigation by the parliamentary standards watchdog.

Gray is understood to have considered evidence on Maltby’s claim that Green appeared to solicit sex from her in exchange for political mentoring, and separate allegations about porn being found on his office computer in a police raid almost a decade ago.

In an article last month for the Times which prompted the inquiry, Maltby said she had met Green in a Waterloo pub, where she said the MP had offered to help her take steps towards becoming a Conservative candidate. She alleged that he had touched her knee during the meeting, as he mentioned that his wife was “very understanding”.

Maltby described a conversation that touched on affairs of acquaintances. Then, she said, she “felt a fleeting hand against my knee, so brief it was almost deniable”.

The activist said she had avoided Green after their encounter, but then wrote a piece for the Times in 2016 for which she was pictured wearing a corset. Green then texted her unprompted, she said, saying: “Long time no see. But having admired you in a corset in my favourite tabloid, I feel impelled to ask if you are free for a drink anytime?”

The case was one of several that emerged after a string of allegations against the media mogul Harvey Weinstein raised questions about the culture of sexual behaviour in other industries.

A spokesman for the Daily Mail said: “It is outrageous and utterly spurious to link these threats to the Daily Mail. There was nothing in the Mail’s coverage which incited threats of any kind and the Mail unreservedly condemns anyone who has made such threats.”