Fonua-Blake was sent from the field after the siren at Lottoland for an expletive-laden blow-up at a controversial last-minute decision in the hosts' 14-12 defeat.

Television audio clearly picked up the Sea Eagles prop calling referee Grant Atkins a "f***ing retard" before he was marched from the field.

Fonua-Blake was on Monday issued with a grade-three contrary conduct charge, which carries a 300-point base penalty and a possible three-game suspension.

But it also means he can reduce the ban to two matches with an early plea.

Sunday's incident came after Manly were angered by not being awarded a penalty when winger Tevita Funa appeared to be pushed while chasing his own kick.

On Monday afternoon he NRL's head of football Graham Annesley stopped short of admitting the Sea Eagles were robbed of a chance to level the scores on fulltime.

While Annesley would have awarded a penalty, he said it came down to a difference of opinion for video referee Jared Maxwell after multiple reviews on Monday morning.

Annesley said Newcastle's Bradman Best had less than half a second from when the ball hit Funa's boot to time of contact to pull out of the tackle.

"That's the nature of our game, these are judgement calls, they are not black and white calls and someone has to make a decision. In this case, the bunker made the decision," he said.

"I just don't have to agree with the decision that they made in this case."

However, he said discretion needs to stay with the bunker and on-field referees to make these calls rather than a blanket rule for late contact.

Fonua-Blake has until midday on Tuesday to decide whether he will contest the grade-three charge.

The contrite Manly firebrand immediately apologised after coming off the field, and again later in a statement issued by his NRL club.

"Referees have a very tough job and we all need to respect their decisions even when we may not agree with them," Fonua-Blake said.

"I should not have let my emotions get the better of me and I am very sorry for the comments I made.

"I'd also like to offer my sincere apology to anyone offended by the regrettable language that I used.

"I let myself and my club down. That is not who I am or what this club stands for."

Meanwhile, Wests Tigers centre Joey Leilua has copped a four-game ban for his swinging arm on Penrith fullback Dylan Edwards on Saturday night.

The Tigers on Monday confirmed Leilua has taken the early guilty plea for the grade-three dangerous contact charge on an unsuspecting Edwards.

Sea Eagles forward Martin Taupau escaped sanction for a high shot on Knights second-rower Sione Mata'utia.

Australian Associated Press