A man who punched his three-year-old daughter so hard that he broke her jaw has been jailed for 16 months.The 30-year-old single father, who was living in East Cambridgeshire, lashed out at his daughter after she began 'messing around' in her bedroom.The cruel blow broke the youngster’s jaw and caused two painful fractures either side of her mouth. However, the man - who cannot be named for legal reasons - failed to take his daughter to hospital immediately and later claimed she sustained the injuries after falling over in a park.Sentencing him at Cambridge Crown Court Judge Jonathan Haworth said he had 'abused' his position of power.He said: 'You were the sole carer of a three-year-old child and you hit her so hard she fell off the stool. It was a deliberate blow to a vulnerable victim. This was an abuse of your position of trust as carer for the child and you failed to seek any medical assistance for her as you put your fear of punishment ahead of her need for medical treatment.'He initially told police his daughter sustained injuries when she fell over at a play park but later admitted punching her at his home.He admitted assault occasioning grievous bodily harm and child cruelty for needlessly leaving the girl unattended in her room.The 30-year-old was sentenced to 16 months in jail for assault and three months for child cruelty, which will be served concurrently.Robert O’Sullivan, prosecuting, said the man told police he had been sitting in his daughter’s room when she started 'messing around'.He said: 'When officers put it to him that he must have used considerable force he said "perhaps I hit her quite hard then".'Roger Harrison, mitigating, described the man as a 'dedicated father' and said the fractures were as a result of the girl falling on the floor, not his punch.