Parents at a primary school have been issued warnings about popular children’s app, Roblox, which has been found to contain naked characters and inappropriate messages.

They are being urged to check their child’s account about the game, which is aimed at youngsters aged between five and 10.

Staff at Bredhurst Primary sent out the message after it was discovered 70 pupils were playing the game.

Most of them disclosed they had online “friends” whom their parents did not know about.

The children said they had seen messages from strangers and seen naked characters, some “doing very adult things”.

This is said to include 'Lego-type' characters having sex.

However, there is confusion over the letter as the police, who are said to have spoken to youngsters at the school, say they have no knowledge of the problem.

The letter, sent out on Friday, said: "We would advise every parent to check their child’s Roblox account and look to see if they have friends that they did not know.

"Many of the children we spoke to yesterday said their accounts were “maxed out” meaning they have 200 online friends.

“We would also ask parents to check the child’s 'in game' message inbox to check if they have been receiving inappropriate messages.”

A spokesman for the Church of England school said it would be issuing a statement later.