Millwall have signed defender Tony Craig on a two-year deal.
Former Arsenal, Tottenham and England defender Sol Campbell has announced his retirement from football.
Campbell, 37, was released by Newcastle at the end of last season and has not been able to secure a new deal with another club, partly due to injury.
He told Sky Sports News: "It was a very hard decision. It's hard to let go when you have been a top sportsman for a long, long time.
"To say that I am not going to play professional football again is difficult because I've had a long time at the top and I've put in a lot of work and it's taken a lot of dedication.
"I had a couple of offers to carry on - one from a Premier League team, and another from a team who have just been promoted to the Premier League, but I had a foot injury and by the time I'd recovered from that people had already moved on."
Campbell rose through the ranks at Tottenham before making a controversial move to bitter rivals Arsenal in 2001.
The transfer led to a deluge of criticism from Spurs fans, who labelled him "Judas" for moving across the famous north London divide, but the decision proved to be a wise one as he went on to enjoy a hugely successful five-year spell with the Gunners.
The centre-half was part of the 2003-04 'Invincibles' team, and lifted three Barclays Premier League trophies and two FA Cups during his time at the club.
The Londoner also scored Arsenal's only goal in their 2006 Champions League final defeat to Barcelona.
The big centre-back won 73 caps for England and represented his country at six consecutive major international tournaments.
After leaving Arsenal Campbell joined Portsmouth, where he won the FA Cup in 2008.
He returned to the Gunners for a brief second spell two years ago and also played for npower League Two side Notts County before his final playing stint at Newcastle, where he made just eight appearances in the 2010-11 season.