Ange Postecoglou's Celtic have signed Argentinian left-back Alexandro Bernabei on a five-year contract.

The 21-year-old moves to the Scottish champions from Lanus in his homeland's top division for a fee reported to be 3.75 million pounds ($A6.6 million).

Bernabei, an Under-23 international, will become the first player from Argentina to play for Celtic.

"I spoke to the manager and he said he believed in me and my quality and that I can adapt to the team quickly," he said of his conversations with ex-Socceroos coach Postecoglou.

"I feel proud to be playing in Europe because it was one of my dreams and I'm excited to train with and play with my new team-mates.

"The stadium is just incredible. The people, the club, team-mates, and the coaching staff are all incredible.

"I'm very excited and happy and I can't wait to be playing in the Champions League. I've heard that the people are crazy, so I can't wait to sense that feeling and emotion in Celtic Park."

Bernabei is the second new face to arrive at Celtic Park this summer following the signing of goalkeeper Benjamin Siegrist, while defender Cameron Carter-Vickers, who shone on loan last term, has joined permanently from Tottenham.