Following the revelations, it was reported by Buzzfeed that the journalist also contacted a series of other politicians and also sent them flattering and flirtatious tweets. Although some replied, there are no suggestions any of their messages contained inappropriate content.
The fake Twitter account has since been deleted, but the methods used to acquire the story have led some to question whether the 'sting' could be considered a fishing expedition to try and ensnare politicians.
The Independent Press Standards Organisation (Ipso) editors' code of practice states: "Everyone is entitled to respect for his or her private and family life, home, health and correspondence, including digital communications."
The editors' code goes on to say: "Engaging in misrepresentation or subterfuge, including by agents or intermediaries, can generally be justified only in the public interest and then only when the material cannot be obtained by other means."
The Sunday Mirror said that the journalist, with whom the paper was working on a freelance basis, was carrying out an undercover probe into claims by sources that MPs were using social media networks to meet women.
For the sting operation against Mr Newmark, a male journalist had reportedly set up a Twitter profile under the name of "Sophie Wittams" and used a picture of a blonde woman. The bio read: "Twenty-something Tory PR girl."
In his resignation statement on Saturday, Newmark said: "I have decided to resign as minister for civil society having been notified of a story to be published in a Sunday newspaper.
"I would like to appeal for the privacy of my family to be respected at this time.
"I remain a loyal supporter of this government as its long-term economic plan continues to deliver for the British people."
Rob Wilson, Conservative MP for Reading East, has been named as Newmark's replacement at the Cabinet Office.
Newmark's resignation was made on the eve of the last Conservative party conference before next year's general election.
Hours earlier, fellow Tory MP Mark Reckless defected to UKIP, forcing a by-election and plunging the party into crisis.
- UK Independent
