US boxing champion Floyd Mayweather Jr has been arrested 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 mobile phone, but police said they are urging prosecutors to bring an additional charge of domestic battery based on the complaint of his ex-girlfriend.

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

Cassell said police were called to the woman's home 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 on Friday.

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 US athletes compiled by Sports Illustrated magazine, Mayweather ranks third with total earnings of $60.3 million, behind golfers Tiger Woods and Phil Mickelson.