Pereira is set to return for Albion at Millwall on Sunday after a three-game ban for his retrospective punishment in the home defeat by Stoke City.

But Bilic felt Pereira was harshly dealt with following his altercation with Stoke midfielder Joe Allen.

"As a club we try to be polite but we are disappointed and angry," he said.

"The explanations were basically primary school level," he told BBC WM 95.6. "And that makes you even more disappointed and angry."

Although the elbowing incident in the 35th minute of Albion's 1-0 defeat was missed by match referee Tim Robinson, it was picked up on video evidence and Pereira accepted his charge of violent conduct and his three-match suspension.

When asked to draw comparison with recent incidents involving players from two of Albion's main promotion rivals - Leeds United midfielder Mateusz Klich and Brentford forward Said Benrahma - Bilic said: "Very similar things happened."

Benrahma went on to score two goals to complete a hat-trick in a 5-1 win at Hull after TV replays appeared to show his elbow connecting with the Tigers' Stephen Kingsley.

Klich also escaped retrospective punishment despite footage appearing to show him treading on Millwall striker Tom Bradshaw while he was on the floor.

"Everyone was talking about how hard done by Leeds were with one or two decisions," said Millwall boss Gary Rowett. "But probably the major decision went against us. He has definitely trodden on our player. I saw the footage after the game and it should have been a red card."

"It's simply not right," added Bilic. "I don't want players banned. But, at this stage of the season, when everything matters, you want fair and right decision from the FA."

The only plus point Bilic has taken is that Pereira has come back refreshed from his enforced break, having been allowed to return home to Portugal.

"We've used this ban in a good way to rest him physically and mentally," he said.

"He needed a rest. He has become a target for opponents, closing him down, challenging him, fouling him. He has had a lot on his shoulders."