Ifill started his career with Millwall

The former Millwall player, 27, returns to London after agreeing a deal running until June 2009.

Ifill joined the Blades in May 2005 but after helping them to promotion last season he has made only three Premiership appearances this term.

He said: "I have come to a club that is geared for the Premiership again and that is what we are hoping for."

Ifill added: "It wasn't a difficult choice and I'm looking forward to it now.

"I had been talking to another club but my agent rang and told me that Palace were interested and from there it was pretty straightforward really.

"People will know I used to be at Millwall, so I know the area and I know a few of the lads and that makes it easier in that respect."