Avon and Somerset Police said the boy, who cannot be named because of his age, will appear at Bristol Magistrates' Court on Monday.

Anthony Snook, 44, and two other boys, aged 15 and 16, have already been charged with two counts of murder.

Mason, 15, and Max, 16, were stabbed in Knowle West, Bristol.

They were rushed to two hospitals - Southmead Hospital and Bristol Royal Hospital for Children - by ambulance, where they died early on Saturday 27 January.

It comes after police made two more arrests in the case, bringing the total detained during the investigation to 12.

Detectives said a 49-year-old woman and a 14-year-old girl were arrested on suspicion of assisting an offender in relation to Mason and Max's deaths on Sunday.

They remain in custody, along with a 14-year-old boy who was arrested on suspicion of murder on Friday, police said on Sunday evening.

Avon and Somerset Police said out of the 12 people arrested as part of the murder inquiry so far, six have now been charged.

Along with the four charged with murder, two have been charged with assisting an offender.

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Speaking earlier on Sunday, Detective Superintendent Gary Haskins said: "A dozen people have now been arrested since the tragic events in south Bristol last weekend.

"Mason and Max's families are being supported by specialist family liaison officers...

"We are hugely grateful for the support the local community have shown us over the past week and we will continue to inform the public of any significant updates regarding this ongoing investigation."