Pressure has intensified on the Conservative Party after a Norfolk MP's aide has spoken of her concern about its inaction over David Ruffley's caution for common assault.

Katie Pruszynski, who has worked as an aide to Norwich MP Chloe Smith in Westminster for three years, wrote to Tory whip Claire Perry on Wednesday demanding answers about why another female MP was temporarily suspended from the party for appearing on television, yet it has drawn a line under the assault by the Bury St Edmunds MP.

Mr Ruffley accepted a caution for common assault on his partner Wendy Drew in March, and his party association's executive committee, which re-selected him as their candidate for the general election shortly afterwards, have since given him their support. Despite repeated attempts to contact him for a statement, Mr Ruffley has refused to comment.

Ms Pruszynski said she had spoken to Ms Smith, who she described as a 'model employer', before sending the email to the Whips office, and was told her boss did not object.

But she said: 'This is entirely separate to Chloe. This is about being a member of the Conservative party and a female member of the Conservative party deeply concerned about the message it sends to the people to whom we are trying to say - 'we are the guardians of your interests and wellbeing'.' She said she had not wanted the email to be made public, but had sent it to a few other staff members in the House of Commons, and the email was subsequently leaked to a political blog. In the email to Ms Perry, Ms Pruszynski said she was very concerned about reports of his caution, and called on the party to explain to her why the party and the whips believed that it was appropriate for him to continue as an elected representative of the party.

She said it seemed an 'outrageous inconsistency' that Nadine Dorries had the whip suspended for her appearance on a television show and Mr Ruffley was allowed to remain.

'While I understand that the police have concluded their involvement in the matter, I would like to state in the strongest possible terms that his continuing presence as a representative of the party, and of parliament, is grossly at odds with our purported moral compass.'

Her email concluded: 'You have campaigned passionately for the protection of children from sexualisation, and for the protection of women from domestic violence. I hope that you will be able to shine some light on the inexplicable stance on Mr Ruffley.'

Labour MP Eric Joyce lost the Labour whip when he was charged with three counts of common assault after being detained by police following reports of a disturbance in a House of Commons bar. Mid-Bedfordshire Conservative MP Ms Dorries was suspended by the party in 2012 following her appearance on the TV reality show I'm a Celebrity, Get Me Out of Here. She sat as an independent until the Tory whip was restored in May last year.

Ms Smith could not be reached for a comment.

Suffolk Coastal MP Therese Coffey said: 'It is difficult for me to comment as Mr Ruffley has not made any comment. But the police have dealt with the situation and he accepted a caution for common assault.'