Middlesbrough boss Gareth Southgate has confirmed to BBC Radio Cleveland that Abel Xavier is training with the club.
Xavier had his drugs ban reduced
Portuguese defender Xavier received an 18-month ban in November 2005 after failing a drugs test following Boro's Uefa Cup tie against Greek side Xanthi.
Boro cancelled the 33-year-old Xavier's contract in January after an appeal to Uefa failed.
But Xavier took his case to the Court of Arbitration for Sport, which reduced his ban by six months.
The Portugal international joined Boro in August 2005 on a one-year contract.
Xavier became the first Premiership player to be found guilty of taking performance-enhancing drugs.
A routine test after Boro's Uefa Cup tie against Xanthi in September 2005 showed the presence of dianabol, a steroid favoured by body-builders.
The six-month reduction of his ban means Xavier will be be able to resume playing in November.
The experienced defender played for both Liverpool and Everton, as well as Benfica, Galatasaray and PSV Eindhoven, and been capped 20 times by Portugal.