Malky Mackay should face a season-long ban from football for the offensive texts he sent to a former colleague at Cardiff, according to ex-Football Association chairman Lord Triesman.

Former Cardiff manager Mackay has apologised for sending three messages to the club’s ex-head of recruitment Iain Moody which he admits were “unacceptable” and “inappropriate.” The texts were published in a newspaper, with details of four further messages it alleges were of an offensive nature on Saturday.

One of those, it is claimed by the paper, makes a racist reference to Cardiff’s Malaysian owner Vincent Tan. The other three are of a sexist and homophobic nature, it is alleged.

The FA has confirmed it is investigating the dossier of messages involving Moody and Mackay sent to it by Cardiff but it may be unable to sanction either man if the messages are deemed to be private correspondence.

Triesman, who served as FA chairman between 2008 and 2010, believes Mackay should be barred from the game for a season solely on the strength of the three messages he admits sending, should the FA have jurisdiction to act.

“There could very well be a significant period in which he can take no part in football,” Triesman said.

“If it turns out to be three texts then maybe a season (ban), if it’s more than that it may be much more.”

He added: “Assuming that the evidence is stacked up — I can’t pre-try it — I think the FA, in the same sense that it can say to players ‘here is a period in which you can take no part in playing,’ could do so with other people in football.”

In May, the FA said it would not sanction Premier League chief executive Richard Scudamore over emails of a sexist nature which he sent.

Current FA chairman Greg Dyke said at the time: “The FA does not as a matter of policy consider private communications sent with a legitimate expectation of privacy to amount to professional misconduct.”