The Brazilian joined the Reds last summer before being sent out on loan to Finnish side SJK where he helped them win their first ever league title.
He returned to Liverpool in November but was loaned out again to Belgian side Sint-Truidense as he had not been granted a work permit to play for Liverpool.
The 19-year-old impressed Klopp while training with the first team and after Allan was called up to the Brazil Under-20 side, the German spoke of his potential.
He said: “When I came here, one or two months later Allan was here and I said ‘who is this?’. ‘He is a player for us and the week before he became a champion in Finland.’ ‘Interesting – why didn’t he play here?’ ‘Because it’s not possible.’ And then I started learning about the FA rules and things like this.
“I saw him in training and I thought ‘oh my God, what can we do to keep this boy here and bring him into the line-up?’ He’s 19 years old, an outstanding talent, a good player with a good attitude, everybody loves him, he’s a nice lad – so that’s really, really good. He’s a smart player.
“There is no chance in this moment here because he can’t get the permission to play here, so we have to send him out on loan. We sent him to Belgium and he did well, really well until now. We had no doubts about this, it was a good transfer for both sides.
“Now for the first time he has got an invitation for the national U20 team, and that’s great. It’s really deserved because he’s an outstanding talent. Everybody has seen him, but it’s not too easy to have a lot of pictures of him because most of the time he has played in other countries.
“We hope we can find a solution in the future because he will be a fixed part of the squad in the future, for sure. Now he uses this time to improve and the next step to the U20 national team of Brazil is a great story.”