A headteacher has sent a letter to parents following concerns that children as young as six are re-enacting scenes from adult video game series Grand Theft Auto.

Young pupils have been initiating games involving "simulating rape and sexual intercourse" as well as having playground chats about "drug use", according to Coed-y-Brain Primary School head Morian Morgan.

Staff at the school in Llanbradach, Caerphilly, blame the worrying behaviour on the 18-rated and violent computer game series Grand Theft Auto, which sees players take on the role of criminals in America's dark and seedy underworld.

Latest instalment GTA V is thought to be one of the best-selling video games of all time, having sold more than 32 million copies worldwide.

A letter sent to parents said children were "acting out scenes from the game which include the strongest of sexual swear words", "having conversations" about sexual acts and "play acting extremely violent games that sometimes result in actual injury".

Speaking to the South Wales Argus, Mr Morgan insisted the letter was simply a way of making parents aware of this trend, rather than criticising them.

"Until I went online and checked the content of this game, I thought it was just a bit of swearing and some shooting and I think some of the parents will tell you that they have been equally naive," he told the newspaper.

"But I must stress it's not a matter of me condemning parents at all."