Newcastle boss Bobby Robson has signed French youngster Olivier Bernard to boost his defence.

The 20-year-old Lyon star has joined the club on a free transfer and could come straight into contention as United face the prospect of competing in the Premiership over the next two months with few options at the back.

Greek international Nikos Dabizas is out for two months after undergoing surgery on a knee cartilage injury, while Spaniard Marcelino will be missing for six weeks with a snapped tendon in his finger.

With Steve Howey having joined Manchester City, Robson was left with just two experienced central defenders - Aaron Hughes and Alain Goma - for the game against Tottenham at the weekend, and while they both performed admirably, there was little tried and tested cover available to the manager.

"Olivier Bernard has signed a contract and joined us on a free transfer," a club spokesman confirmed.

Talks United are also understood to be in talks with the South American's representatives with a view to a �2m deal which would bring Chilean central midfielder Clarence Acuna from cash-strapped Universidad de Chile.

The 25-year-old international found himself the centre of attention after failing a drugs test following his country's World Cup qualifier against Peru in April, but he has always pleaded his innocence and has since persuaded a Fifa panel that he did nothing wrong.

Acuna would become the fifth South American player in Robson's first-team squad, alongside the injured Bassedas, Nolberto Solano, Diego Gavilan and Cordone, who has scored twice in his first three games for the club.