A French Catholic priest was forced to retire after he was caught slapping a crying two-year-old baby during a baptism ceremony.

In 40-second footage that went viral online, the priest was seen slapping the boy on the cheek while telling him to 'be quiet' and to 'calm down.'

People can be heard telling the priest, 'Don't hit the kid,' and 'Sir, we do not hit him,' but he appears to ignore their pleas.

The priest continued to hold on to the boy by the head, as the mother told him to let go. The shocked parents eventually managed to pull the child out of his hands as another woman tried to intervene.

The ceremony took place at the Collegiate Church in Champeaux, in the south-eastern suburbs of Paris on Sunday, according to the Daily Mail, which identified the priest as 89-year-old Father Jacques Lacroix.

The newspaper reported that Lacroix's apology has been accepted by the family and that he has since announced his retirement. The newspaper also said that Lacroix had told France Info radio that he had been trying to calm the child down.

'It was somewhere between a caress and a slap, I hoped to calm him down, I didn't know what to do. The child was screaming a lot and I had to turn his head to pour water over it,' he said.

'I told him to "calm down, calm down" but he was not calming down. I tried to hold him close. I just wanted him to calm down. I apologised for my clumsiness to the family. I am finishing my ministry now, it was my last baptism, there is an end to everything,' he continued.

The Diocese of Meaux issued a statement, explaining that Lacroix's actions were due to fatigue, although it added, 'that doesn't excuse it.'

Jean-Yves, the Bishop of Meaux, announced that Lacroix will no longer conduct baptism and marriage ceremonies and will only be allowed to celebrate mass in the future if he has clearance.