A US judge rejected Tuesday a request by jailed former sports star O.J. Simpson for a retrial over his conviction for a 2007 casino robbery and kidnapping in Las Vegas.

A lawyer for the disgraced ex-American footballer and actor, who was infamously acquitted of murdering his ex wife in 1994, said the 66-year-old will appeal the ruling.

Simpson, who was jailed for up to 33 years for the September 13, 2007 incident, testified in seeking a retrial in May on grounds that his longtime lawyer Yale Galanter had botched his defense.

On Tuesday, Clark County Judge Linda Marie Bell, who heard his testimony over five days in May, refused his petition for a retrial.

"Mr. Simpson failed to establish that appellate and trial counsel were ineffective or that any deficient performance by counsel resulted in prejudice," said the 101-page ruling, a copy of which was obtained by AFP.

"Given the overwhelming amount of evidence, neither the errors in this case, nor the errors collectively, cause this court to question the validity of Mr. Simpson?s conviction.?

She added: "All grounds in the petition lack meter and, consequently, are denied."

Simpson is serving nine to 33 years in a Nevada state penitentiary after being convicted in October 2008 of armed robbery, assault and kidnapping over the robbery, which was caught on security camera footage.

One of his attorneys, Osvaldo Fumo, said he would appeal.

"Mr. Simpson will be vindicated. I have not given up this fight," he told AFP.

Appearing in court in May, Simpson looked much heavier than in his earlier days, or in his notorious mid-1990s murder trial.

Dressed in a blue prison outfit, Simpson said he did not knowingly break the law on the day he and five associates seized what he believed were his own stolen belongings from two sports memorabilia dealers.

"It was my stuff. I followed what I thought was the law... I didn't break into anybody's room, I didn't beat up anybody, I didn't try to muscle the guys," he told the court in Las Vegas.

In July, Simpson -- acquitted of murdering his ex-wife Nicole Brown Simpson and her friend in 1995 -- was granted parole for offenses related to the 2008 conviction but still faces years behind bars.

Specifically he won parole for counts of kidnapping, robbery and burglary with a firearm, the Nevada Board of Parole Commissioners said.

At the time parole hearing examiner David Smith said in an email to AFP that Simpson had been paroled due to his "positive institutional conduct, participation in programs, lack of prior conviction history."

However, Simpson still had to serve at least 12 months on four concurrent sentences for using a weapon during the robbery and kidnapping. He then will face further back-to-back sentences of at least 18 months each for sentences of assault with a deadly weapon, making a total of at least four years.

One of the most famous American football players of his generation during a glittering 1970s career, Simpson was the prime suspect in the brutal 1994 murders of his ex-wife Nicole and her friend Ron Goldman.

Simpson, who has always vehemently denied the killings, was acquitted after a racially charged 1995 trial in Los Angeles, in a verdict that was greeted with widespread outrage across America.

He was subsequently found liable for the deaths in a 1997 civil suit and was ordered to pay damages to the victims' families totaling $33.5 million.

He has repeatedly said he will not pay the damages.

[Image via Agence France-Presse]