An undercover reporter working for Al Jazeera is believed to have gained access to the Labour Party conference by using a junior Israeli embassy official as his referee.
The reporter, who adopted the false identity of "Robin Harrow", was vouched for by Shai Masot, an aide at the embassy, the JC understands.
The use of Mr Masot's name meant the reporter’s application was not flagged up for further security checks prior to the Liverpool conference.
The undercover journalist is thought to have filled in a registration form for the conference under his false identity using a Labour Party membership he had set up in the same name.