A Swansea Crown Court judge sentence a man to a 16-month jail term for torturing his teenage girlfriend, who he allegedly accused of flirting and cheating via the popular social media site Facebook.

Court records showed that Judge Keith Thomas also slapped the defendant, identified as 37-year-old Jason Fleming, of a restraining order that would prevent him from coming any near to the young victim.

According to the UK-based Daily Mail, Fleming pleaded no contest in assaulting 18-year-old Jessica Herbert, who prosecutors said was tortured into revealing her Facebook log-in details.

"He stamped on the teenager and put a black plastic bag over her head in a bid to reveal her log-in details," the Daily Mail was reported as saying on its report.

Prosecutors who handled the case informed that court that at one point, Herbert was attacked so viciously by Fleming that she fainted and was unable to recall all the sufferings that she endured at the hands of her obsessed boyfriend, who is almost two decades her senior.

Court accounts revealed that Fleming pierced Herbert's ear with a pencil and subjected her to "a cold bath until she admitted having an affair.".

Upon discovering that the young woman has male friends on her Facebook account, Judge Thomas revealed that Fleming "put a black bag over (Herbert's) head ... tied her hands and picked her up by the throat."

"You were obsessively jealous of her and took it out on her that she had male friends ... In an arrogant bullying fashion you dictated that you were in charge of her and she would do whatever you chose," Thomas was quoted by The West Australian as saying in his decision.

The court judge also noted that Fleming has had records of hurting and abusing women and everything that the defendant had unleashed against the teenage victim can be considered as 'elements of torture'.