The Conservative Party faces a ­potential fine of up to £2m after its software for conference delegates exposed the personal details of thousands of MPs and attendees, including Cabinet ­ministers.

As the Prime Minister arrived in ­Birmingham for the annual conference last night, her party headquarters was scrambling to lock down a function on its mobile phone application that ­allowed anyone to log in as an MP or a speaker, exposing their private contact details.

Last night ministers and senior MPs reacted with fury after the blunder was revealed on social media, where ­images posted on Twitter showed ­users logging in as Boris Johnson, the former foreign secretary, among other senior figures.

A government source raised concerns about the potential ­security implications for Cabinet ­ministers, given that mobile numbers can be used to track the location of ­associated telephones.

It came as Theresa May prepared to face down Brexiteer MPs and former ministers, including Mr Johnson and David Davis, the former Brexit ­secretary, amid a major clash over the Government’s Brexit policy.

On today’s opening day of the ­conference, she is due to attend a meeting of the National Conservative ­Convention, the assembly of Tory ­volunteers, where many activists are likely to express anger over her ­Chequers blueprint for Brexit.