The Belgian club's official website mentioned that the promising left-back, who will be put through his paces during the next few days, would sign a permanent deal if he impressed.
Lierse tactician Herman Helleputte decided to try Attwa out on Friday, as he named the up-and-coming defender for a match with the reserves.
The Red Devils' winger, who was targeted by Zamalek early this season, featured for Ahli's first team on more than one occasion.
But at the beginning of the current season, Attwa decided to take no part in his team's training sessions, and he has been seeking to move away from the club ever since.
He was on the brink of joining Zamalek last summer, but the regulations prevented him from sealing the move.
Attwa has previously stated that he has no intention to play for Ahli again, saying he would either start a new adventure with Zamalek or carry on his career abroad.
Lierse, owned by Egyptian businessman Maged Sami, have already five Egyptian players at their disposal - Ahmed Samir, Mohamed Abdul Wahed, Sherif Al-Beyali, Youssef Fawaz and Islam Shokri.
For this reason, Attwa would easily settle down at the second tier among his compatriots should the deal go through.