* Real say they did everything needed to complete deal
* Club hints failure of transfer was caused by United (Adds details)
MADRID, Sept 1 (Reuters) - Real Madrid said on Tuesday they had done everything needed to complete the signing of goalkeeper David De Gea from Manchester United before Monday's midnight deadline and hinted that the English club were to blame for the deal's failure.
Spain goalkeeper De Gea was all set to join Real but is now facing an uncertain future after the paperwork failed to arrive at the Spanish league in time and was not entered correctly into FIFA's Transfer Matching System (TMS) as required.
Real said in a statement on their website (www.realmadrid.com) the delay was not their fault and detailed exhaustively how and why the necessary documents were not ready until it was too late.
United had not initiated talks on a possible deal, which included the English club buying Real's Costa Rica keeper Keylor Navas, until Monday morning, the statement said.
After initial agreement was reached, Real said they sent the contracts to United at 1:39 p.m. Spanish time (1139 GMT).
Eight hours later they were sent back with "small modifications", which Real said they immediately accepted.
Real then sent the contracts signed by De Gea and Navas back to United for their signature at 21:32 GMT, 28 minutes before the deadline.
United entered the details of De Gea's transfer into TMS at midnight Spanish time but did not put in details of the Navas deal and by then it was too late for Real to access the system, the said.
TMS gave them a last chance to register the deal around half an hour later and Real also sent the documents to the Spanish league even though they knew the deadline had passed.
"Real Madrid did everything necessary, and at all times, to complete these two transfers," Real's statement concluded. (Reporting by Iain Rogers, editing by Clare Fallon)