LAS VEGAS (REUTERS) - OJ Simpson, the former football star famously acquitted of murder in 1995, offered sometimes emotional testimony in a packed Las Vegas courtroom on Wednesday as he sought a new trial in a robbery case that sent him to prison nearly five years ago.

Simpson, 65, was brought to court from a Nevada prison and took the witness stand on the third day of a week-long hearing into his claims that his lead defence attorney, Mr Yale Galanter, mishandled his case in a Nevada trial in 2008.

Simpson is serving up to 33 years for his conviction on 12 charges including armed robbery and kidnapping.

The charges stemmed from a Sept 13, 2007, incident in which Simpson and five other men stormed into a room at the Palace Station Hotel and Casino and took thousands of dollars in memorabilia at gunpoint from a pair of sports collectors.

Simpson was found guilty in October, 2008. Defence lawyers had argued that he was merely trying to recover stolen property, unaware that one of his associates had brought a gun.

His current attorneys have asked a judge to throw out the conviction on the grounds that Mr Galanter had a conflict of interest because he knew in advance that Simpson planned to confront the sports dealers at the hotel.

They also said Mr Galanter never told Simpson that prosecutors had offered a plea deal that included a sentence of two to five years in prison.

A separate appeal by Simpson of his conviction in the case was rejected by the Nevada Supreme Court in 2010.

Appearing older, grayer and heavier after five years behind bars, Simpson told the court Mr Galanter had advised him that his plans were legal the night before the incident.

'I DIDN'T BEAT UP ANYBODY'

The former star athlete said Mr Galanter told him during a dinner discussion in Las Vegas: "you have the right to get your stuff" but cautioned he could not trespass on private property.

Simpson said he told Mr Galanter that if the suit he wore during his sensational 1990s murder trial was included among the memorabilia he planned to burn it, and Mr Galanter responded:"You're not going to burn it, you're going to bring it to me."

Asked by his current attorney, Ms Patricia Palm, if he thought the hotel room scheme was legal, he responded: "Yes I did. It was my stuff. I followed what I though the law was. My lawyer told me 'You can't break into a guy's room' and I didn't break into the room. I didn't beat up anybody."

He added: "And the guys acknowledged it was my stuff, even though they claimed they didn't steal it."

Simpson repeatedly and emphatically denied from the witness stand that the use of guns was discussed ahead of the hotel room confrontation and said he had not been aware that one of the men with him was carrying one.

He became emotional, pausing briefly in his testimony, when discussing the property he said he was told was to be found in addition to the memorabilia, which included pictures of his deceased daughter and parents.

"I thought this is stuff I should have, not some guy selling it in a hotel in Vegas," he said.

Simpson, a former star NFL running back turned TV pitch man and actor, was accused of the 1994 stabbing and slashing murders of his ex-wife Nicole Brown Simpson and her friend, waiter Ronald Goldman.

He was acquitted in 1995 after sensational proceedings carried live gavel-to-gavel on United States (US) television, dubbed the "Trial of the Century" by various media outlets.

A civil jury later found him liable for the deaths of his former spouse and Goldman in a wrongful death lawsuit, awarding their families US$33.5 million (S$41.6 million) in damages.