A former Wales rugby player accused of assaulting a primary school pupil told police he was trying to stop the child assaulting other members of staff, a court has heard.

Matthew Back, 53, who played four times for Wales and has been a teacher since 1994, denies assault.

The child became angry when a paper aeroplane he had made was mistaken for scrap paper and thrown away, the jury at Cardiff Crown Court was told.

The jury was shown CCTV footage from the classroom on the day of the alleged assault, in which Mr Back was seen putting the boy on a sofa in what was called the “zen zone”.

His police interview was read in court in which he told detectives that he intervened when the child became “very aggressive.”

He told officers that the boy had a “history of grabbing” female members of staff by the genitalia and he wanted to stop him from doing it again.

“The very last resort is physical intervention,” he told detectives, adding that staff were trained in restraint techniques.

During his interview, which the court heard he attended voluntarily, he said the boy’s behaviour was often challenging.

He said his response was “reasonable and proportionate” given that he was worried his female colleagues may be assaulted.

He said the boy was also threatening one of the other children in the classroom.

Mr Back told detectives that he intervened and “physically picked him up and escorted him” to the “zen zone”.

He said the boy was telling staff that he hated them and wanted to kill them.

The court heard incidents of this nature were recorded in a document called a physical intervention form and sent within 24 hours to the local authority’s safeguarding team.

In this case, the incident happened at the end of the school day, immediately before a fortnightly meeting with the school’s head and deputy head teachers.

He told police he had planned to fill in the form during the following day’s lunchbreak but by then he had been suspended and was asked to leave the school pending an investigation.

The court heard previously that, at the time, the child had 50 incidents in school which his parents had been informed about, all of which had been documented with paperwork.

But the parents were not informed about the incident in question until they called about a bruise on their son’s arm, a mark which they documented with multiple pictures over the following few days.

They raised concerns with the school and the matter was investigated further, which resulted in Mr Back and two others being suspended.

The Crown Prosecution Service initially decided to take no further action against the three staff members who were then reinterviewed as witnesses rather than as suspects.

Mr Back also told detectives that he enjoyed his job in terms of seeing what progress the children can make, adding: “You get assaulted a lot, but they are mostly fantastic kids.”

He won four caps for Wales as a full-back in 1995 and played club rugby for Pontypridd as well as Bridgend, Swansea, Bristol and Aberavon.

Mr Back, of Miskin, Rhondda Cynon Taf, denies assault.

The trial continues.