An email warning Labour staff that they face disciplinary action if they leak "sensitive or confidential party information" to the media has been leaked to PoliticsHome.

The message was sent by Iain McNicol, the party's general secretary, yesterday afternoon.

It is understood that it was sparked by the leaking of Labour's news "grid" detailing what media events were in the diary for this week.

As reported in the Sun earlier this week the document - marked "private and confidential" - highlighted the fact that Friday is Christmas Jumper Day.

In his email, Mr McNicol said: "Before we all escape the office for a well-deserved Xmas break, I wanted to email you all regarding recent leaks in the media which contain either sensitive or confidential party information.



"I am very clear; no member of staff should pass on information which they think will be used by our opponents to oppose and damage the party and its reputation. This damages the organisation and relationships which we are all trying to build and maintain.



"As laid down in our staff handbook; if a member of staff is found to have leaked confidential information either to a third party with the intent that this is passed on, or directly to a journalist, then disciplinary proceedings will be initiated."

A Labour source said: "This shows how ridiculously over-sensitive the leader's office is."

It emerged last week that the Government had launched a leak inquiry after a letter to civil servants warning about leaks to the media was leaked to the Mail on Sunday.