A Bristol drug user, jailed for at least six years for a campaign of street robberies of women, has had his minimum jail term slashed to four years by top judges in London.

Omar Junior Dinnall, 24, was sentenced at the city's Crown Court in February 2008 after admitting three robberies and asking for another 12 to be taken into consideration.

But Dinnall, of Holly Lodge Road, Speedwell, will now be free to apply for his release after serving only four years after yesterday's decision at the Court of Appeal.

All of Dinnall's offences took place between March 4 and April 11, 2007, when he targeted lone women as they walked, robbing them of handbags and mobile phones.

Violence was used or threatened and, on several occasions, a knife was produced to force the women into handing over their property.

During his spree, he was twice arrested and bailed, only to continue offending. Each time, he tested positive for drugs while in custody.

Sentencing him, the Crown Court judge considered he posed such a risk to the public that he had to be locked up indefinitely and that he should not be able to apply for release until he had served six years.

This week, his lawyers were before Lady Justice Hallett, Mr Justice Simon and Mr Justice Blake at the Court of Appeal, where they argued that both the indefinite nature of the sentence and the minimum term were too long.

"This was a campaign of robberies against vulnerable women," Mr Justice Simon said, upholding the finding that Dinnall was "dangerous" and therefore liable to an indefinite sentence.

He added: "More than trivial injuries were inflicted during the commission of the crimes.There were a significant number of similar matters which he wished to have taken into consideration.

"In our judgment, the judge was fully entitled to find that the test of dangerousness was satisfied."

But, after ruling the minimum term was "manifestly excessive", he added: "In the circumstances, after proper credit for guilty plea, the appropriate specified minimum period is four years, less the 318 days spent on remand."

Dinnall will only be freed after serving his minimum term if he is considered safe for release into the community by the Parole Board.