A father killed his baby son by punching him several times to stop him crying, a court heard.

Paul Oldacre, of Penhill, who has an IQ of just 69, at first told ambulance staff that he had sat on seven-month-old Jamie.

Later he admitted striking him after Jamie's constant crying due to teething had made him reach "boiling point".

A post mortem examination discovered bruising across the boy's rib cage, and three of his ribs were broken. His liver was cut and ruptured and he had internal bleeding.

Bristol Crown Court was told that at an earlier hearing Oldacre, 27, had admitted manslaughter on the grounds on diminished responsibility. But the Crown had rejected his plea, and he is now on trial for murder, which he denies.

A jury was told that on the morning of September 20 last year, Oldacre's wife Sharon went to her job at a factory, leaving him looking after their two children.

At about 4.30pm that afternoon Oldacre telephoned his wife saying he had accidentally sat on Jamie, and that the baby had turned a funny colour.

Mrs Oldacre rushed to their home at Burbage Road with her supervisor and found Jamie lying on the sofa. Her son was pale and his lips were blue.

He was taken to Swindon's Princess Margaret Hospital but died that evening. Roderick Denyer QC, prosecuting, said: "These injuries were consistent with a series of blows with a clenched fist.

"It is clear in the medical evidence that these injuries to Jamie were caused several hours prior to the summoning of the ambulance and the phone call to Sharon."

He said that in all probability Jamie would have been saved if had been treated earlier.

Mr Denyer told the court that Oldacre later admitted to police that he had punched the baby, telling officers that "looking after the kids was getting too much for me, and I couldn't cope ... I took it out on Jamie ... I punched him in the stomach and chest".

Mrs Oldacre said her husband was a loving father who was usually good with their children, and was "deeply upset" when Jamie died.

But the court heard that Oldacre, who has an IQ of just 69, had trouble coping with Jamie while he was teething.

Mr Denyer said Oldacre told police Jamie had woken him crying at 10am, and he admitted "getting a bit funny" because he liked staying in bed.

He gave the baby a bottle but he carried on whingeing.

Mr Denyer said Oldacre told police: "I got angry, that's when I started punching him in the stomach.

"I punched him with both hands, I used my clenched fists and punched him pretty hard. I intended to hurt him to stop him crying."

Mr Denyer said: "We say that a grown man who on his own admission punched a seven-month-old baby not once but five or six times hard on the chest and stomach area clearly intended to do really serious bodily harm."

The case continues.