Staff at Filey Church of England Infant and Junior School, which has pupils as young as four, spotted youngsters acting out scenes from Grand Theft Auto.
Several pupils received the 18-rated best-seller for Christmas, and staff were horrified to see children return from the festive break copying the characters actions.
Headteacher Denise Crosier has now written to parents urging them not to give violent games as gifts.
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“What we encountered when we came back after Christmas were some children who were kicking and pretending to fight, and it became apparent when we spoke to them that they were acting out the games they received as presents,” said the head.
“As soon as I was made aware of this I shared it with governors and raised awareness of the situation with parents.”
The letter issued to parents warned them the adult games the children had played, which included war simulator Call of Duty, were not appropriate for young children.
“Our concern is that these games are age inappropriate,” added the head of the primary, which boasts of “reflecting Christian values” in its motto.
“These children are just not emotionally prepared and can’t cope - it could be very detrimental to their mental health and well-being in the future.”
Both console games are rated 18 by PEGI, the body which dishes out age classifications in Europe.
One mum feels some parents may not realise just what they are buying.
“It isn’t like films, which parents are usually more aware about than video games, and have a big 15 or 18 on them which would stop you buying them,” she said.
“I didn’t even realise video games had age ratings - my kids just ask for them and I will get them for them, so I think it is fantastic the school is raising this issue as many parents will be in the dark about it.”
The Grand Theft Auto series has sold millions of copies worldwide and won scores of industry awards.
However it has been criticised for featuring graphic torture scenes, while weapons used throughout the series include chainsaws and flame-throwers.
The Scarborough News contacted Rockstar, the British firm behind Grand Theft Auto, but it has yet to respond.
Pete Dwyer, corporate director for children’s and young people’s services at North Yorkshire County Council, added: “Our schools have a duty to safeguard and promote the welfare of all children and young people.
“This is a duty shared by the County Council and its partner agencies.
“When, as in this case, a school becomes aware of an issue that it feels could have an impact on the health and wellbeing of its pupils, we would support it bringing its concerns to the attention of parents.”