Matthew Sutor hurt the youngster, who cannot be named for legal reasons, during an incident in south Wales in the summer of 2021.

The 33-year-old initially said the injuries had been caused accidentally but later admitted responsibility.

A sentencing hearing at Cardiff Crown Court heard a paediatrician examined the child after concerns were raised about Sutor’s behaviour and found three bruises including a 5cm bruise to the inner side of the right knee, a 2.5cm bruise on the outer side of the left knee, and a 2.5cm on the outer side of the right knee.

A CT scan also revealed the child had suffered a rib fracture, which had evidence of healing.

When medical professionals ruled out the injuries had been caused accidentally Sutor tried to blame another child for what had happened.

On August 1 last year Sutor confided to another person that he was responsible for the injuries.

When asked if he caused the marks on the child the court heard he responded: “Yes I believe I did but I am not going to tell you details.”

The police were notified and Sutor was arrested.

During his police interview Sutor referred to an incident where some of the injuries were caused.

Prosecutor Tabitha Walker said the defendant accepted he had “squeezed” the youngster “really hard” prompting the child to “let out a high-pitched scream”.

She added: “He said the squeeze was a short sharp burst but was really hard.”

Ms Walker also said the defendant claimed he may have been rough as he had been to the gym and was “still pumped”.

Sutor said he was dealing with stress at the time of the assault and was suffering from financial difficulty and marital issues.

The fractured rib and the bruises were inflicted in two incidents.

Ms Walker said: “They were sustained on separate occasions using excessive force and would have caused excessive pain and discomfort which could not have been caused accidentally.”

Sutor, of Weston-super-Mare, Somerset, admitted two counts of assault occasioning actual bodily harm.

The court heard he had no previous convictions.

In a victim personal statement the child’s mother said the defendant’s actions were “inexcusable” and had caused her child “significant pain”.

She said following the incidents being discovered she “cried uncontrollably every day”.

Sentencing, Recorder Paul Hobson said: “To your everlasting shame you sought to blame [a child] for one of the incidents where it was you who assaulted [the victim] and caused him injury. You will carry that shame for the rest of your life.”

He said the defendant’s “unwillingness to front up to what you had done” meant that “I will view any claim you have shown remorse with great scepticism”.

The judge said the offence amounted to a “loss of temper” but he did not seek medical attention for the child and did not admit responsibility until months later.