Former Cardiff manager Malky Mackay has escaped punishment over his controversial exchange of text messages with Iain Moody.

The English Football Association announced on its website on Thursday it would not be taking any action after a lengthy investigation.

It said it had spoken to both Mackay and Cardiff's former director of communications Moody about the inappropriate nature of the language used, but deemed that the messages were sent "with a legitimate expectation of privacy".

The governing body said both individuals had acknowledged that such terms were not acceptable and pointed out Mackay has voluntarily undertaken equality and diversity training.

Mackay led Cardiff to promotion to the Premier League in May 2013 but he was sacked the following December after falling out with club chairman Vincent Tan.

The 43-year-old Scot became manager of Cardiff's Championship rivals Wigan in November 2014 but was sacked in April as relegation to League One, the English third tier, loomed.

The FA said the messages, sent between June 2011 and March 2014, were obtained by Cardiff in March 2014 and provided to them the following October.

"The FA has undertaken a thorough and detailed investigation in connection with inappropriate language contained within text messages and an email sent by Iain Moody, and text messages sent by Malky Mackay when they were employed by Cardiff City FC," said the FA statement.

"To date, the FA's policy in cases such as this has been to not bring charges in respect of private communications sent with a legitimate expectation of privacy.

"The FA's investigation looked at all aspects of the communications, including the context in which the communications were sent. The evidence was then reviewed by a QC with particular expertise in sports' disciplinary proceedings and employment law.

"Having assessed the evidence, and in light of the finding that the communications were sent with a legitimate expectation of privacy, the FA will not be taking disciplinary action against Iain Moody and Malky Mackay in connection with the content of those messages."

But the judgement drew a fierce backlash, with England striker Eniola Aluko - a member of the squad which recently finished third at the Women's World Cup - joining in the criticism.

"Basically if you're a football coach/manager/leader and racist in private it's ok... Dreadful precedent," Aluko said on her official Twitter account.

The FA also came under attack from the anti-discriminatory group Kick it Out and the Jewish Leadership Council.

"The FA has taken a decision which is undermining its own credibility, commitments and zero tolerance to discriminatory and abusive conduct," Kick it Out chairman Lord Ouseley told Sky Sports.

"It really damages the campaign to tackle unacceptable behaviour in football.

"Some of the emails and texts revealed horrendous statements about people's personality and anyone who cares about equality and fairness will be disappointed to what the FA have done."

Simon Johnson, chief executive of the Jewish Leadership Council, added: "If the FA is determined to have a zero tolerance attitude to racism, anti-Semitism, homophobia and discrimination of any kind, then it is not sustainable to create a distinction between private messages and public comments.

"I call upon the FA to review its disciplinary procedures and to rethink this inconsistent approach."