A secret affair with the potential to rock the Government was revealed last night, leaving David Cameron "stunned".
The identities of those involved cannot be revealed for legal reasons, but is said that the relationship was between two middle-aged figures and has now come to an end.
The revelation could have political implications for David Cameron, who has been hit by a number of scandals recently.
He was said to be “stunned” by the news, the importance of which he realised "immediately".
In meetings the Prime Minister and his aides discussed the potential implications of the affair becoming public, and the damage it could do to major political plans, the Mail on Sunday reported.
“This revelation is dynamite. None of us could believe it when we first heard it. Then we just thought, “What a complete mess”,” a source told the newspaper.
However, a Downing Street spokesman said today: "There have been no crisis talks or meetings."
It is believed that David Cameron has been told about the affair – which has also caused those involved personal distress – in recent weeks.
No current cabinet member is believed to be involved, but it is said that the affair could be as publicly shocking as that between John Major and Edwina Currie which was kept secret for almost two decades.
The news comes as David Cameron faces Tory back-bench revolts over the European referendum and gay marriage and rumours of a leadership challenge.
It also emerged days after Conservative MP Patrick Mercer resigned following a joint cash-for-questions investigation by The Telegraph and the BBC's Panorama
Since then a number of senior politician have become embroiled in the growing Parliamentary lobbying scandal.
The party has also been rocked by allegations of sexual assault against Deputy Speaker Nigel Evans, whose office in the House of Commons was raided last month after a third man came forward and made allegations against the Conservative MP.
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