By Steve Gorman

LOS ANGELES (Reuters) - Boxing champion Floyd Mayweather Jr. was arrested Friday in Las Vegas on suspicion of grand larceny and domestic battery after an ex-girlfriend accused him of beating her in front of their children, according to police and court documents.

Mayweather, 33, who is undefeated in 41 bouts and widely regarded as the best defensive fighter of his generation, was jailed in the Clark County Detention Center in lieu of $3,000 bail, Las Vegas police spokesman Bill Cassell said.

He was initially booked on a charge of grand larceny for the alleged theft of a cell phone, but police said they are urging prosecutors to bring an additional charge of domestic battery based on the complaint of his ex-girlfriend.

Police did not name the woman, but an application she filed in court seeking a protective order against Mayweather identifies her as Josie Harris, with whom the boxer has three young children.

Mayweather's lawyer, Richard Wright, was not immediately available for comment.

Cassell said police were called to the woman's home on Thursday but made no arrests as the couple had merely quarreled

and there was no evidence of a crime.

Officers returned about two hours later when the woman called to report that she had been battered by Mayweather and that he had stolen her phone, Cassell said.

Mayweather was arrested and taken into custody Friday.

Police declined to give further details. But according to an protective order request filed by Harris and posted online by the celebrity news website TMZ.com, Harris accused Mayweather of assaulting her in front of their children.

The flamboyant Mayweather, who lives in Las Vegas and is known by the nickname "Money," fought his latest welterweight bout in May against fellow American Shane Mosley, registering a unanimous points victory that improved his career record to 41-0, including 25 knockouts.

According to a 2010 list of the highest-paid U.S. athletes compiled by Sports Illustrated magazine, Mayweather ranks third with total earnings of $60.3 million, behind golfers Tiger Woods and Phil Mickelson.