Xavier has won 20 caps for Portugal

He was banned for 18 months by Uefa after failing a drugs test in September last year but the suspension was reduced to 12 months on appeal.

Xavier, 33, was sacked by Boro after his positive test but has been training with them for the last few months.

Middlesbrough face Liverpool in a Premiership Reserve League North game at the Racecourse Ground.

Xavier was banned after a routine test following Boro's Uefa Cup tie against Xanthi in September 2005 showed the presence of dianabol, a steroid favoured by body-builders.

He became the first Premiership player to be found guilty of taking performance-enhancing drugs.

The experienced defender played for both Liverpool and Everton, as well as Benfica, Galatasaray and PSV Eindhoven, and been capped 20 times by Portugal.