Mackay, who guided Cardiff to the Premier League after a 51-year wait, was sacked by Malaysian businessman Tan in December 2013, two months after his right-hand man Iain Moody -- now Palace's director of football -- was dismissed by the Welsh club.

Cardiff on Thursday declined to make any public comment on the dossier and the matter is now in the hands of the FA.

The FA has confirmed it has received a detailed account of issues related to Mackay and Moody.

An FA spokesman said: "The FA can confirm it is currently investigating this matter."

The Daily Mail reported the document contains allegations of racist, sexist and homophobic text messages, and the existence of the dossier appears to have closed the door on Scottish boss Mackay succeeding Tony Pulis as Palace manager, according to Britain's Press Association.

Caretaker Palace boss Keith Millen is now expected to take charge of Saturday's home Premier League clash with West Ham.

If Mackay is now no longer being considered by the Eagles, other candidates to fill the vacancy at the Selhurst Park include former Norwich and Newcastle boss Chris Hughton, as well as Tim Sherwood, previously in charge of Tottenham Hotspur.

South London club Palace declined to comment on the situation regarding both Mackay and Moody.

After he was sacked by Cardiff, Mackay launched a �7.5million ($12.4 million, 9.4 million euros) legal claim against Tan for compensation but dropped the claim in May and apologised to the Bluebirds' owner.

Earlier this week Palace were fined by the Premier League for their part in the 'spygate' saga involving Cardiff last April.

The Premier League determined that Palace had breached their 'good faith' rule by obtaining information about Cardiff's team ahead of their 3-0 win when the two clubs were relegation rivals.

The Welsh club had complained to the Premier League that Moody had contacted Cardiff employees for information in the build-up to the game.