Justin Bieber -- Investigated for Battery Against Neighbor

1:34 PM PT -- One of Justin's neighbors tells TMZ ... the argument between Bieber and the accuser was NOT over a party ... it had to do with a Ferrari.

We're told Bieber had the car delivered to his home last night on a flatbed truck ... and this morning, he was racing the vehicle up and down the streets.

Neighborhood sources tell us ... the neighbor was furious about the deafening noise AND felt Justin was endangering the community by tearing through the streets at breakneck speeds.

We're told the neighbor went over to confront Justin about the situation ... and that's when the two sides got into a screaming match.

Justin Bieber has been accused of battery by a neighbor ... and cops are at the singer's home in Calabasas, CA investigating ... TMZ has learned.

Sources tell TMZ .... Justin and one of his male neighbors got into a verbal altercation just after 9 AM. We're told the argument was intense.

We've confirmed Justin has returned from his overseas concerts and was back home this morning.

L.A. County Sheriff's spokesperson Steve Whitmore tells TMZ ... the accuser told deputies Justin made physical contact with him and he has filed a battery report. He also claims Justin threatened him.

Sources connected with Justin's security tell TMZ ... the neighbor came on to Justin's property and began screaming that while Justin was away (overseas) there were people at the house throwing loud parties.

Our sources tell us Justin told the man to get off his property ... but they insist Justin did not have any physical contact with him.

Sources connected with JB's security tell us the singer went inside his house and security escorted the neighbor off the property.