A "peaceful retreat" for Justin Bieber turned into something uglier, his lawyer says, after the Canadian pop star had a run-in with paparazzi in southwestern Ontario.

Bieber has been charged with assault and dangerous driving after a collision involving a minivan and an all-terrain vehicle in southwestern Ontario.

Ontario Provincial Police say the collision occurred Friday afternoon on Line 40 in Perth East township.

"The driver of the ATV and an occupant of the minivan engaged in a physical altercation," according to a police news release.

Bieber, 20, has been released on a promise to appear and is due to appear in a Stratford, Ont., court on Sept. 29.

OPP Sgt. Dave Rektor told CBC News that Bieber was on the ATV, along with a passenger.

He said officers responded to the collision Friday, though Bieber was charged on Monday, when he turned himself in at a local police station.

Rektor said the other party involved in the altercation was not charged.

The pop star's lawyer, Brian H. Greenspan, released a statement indicating that Bieber is co-operating with police.

"Justin Bieber and Selena Gomez's peaceful retreat in Stratford this weekend was unfortunately disrupted by the unwelcome presence of paparazzi," the statement said.

OPP at Perth East home of Jeremy Bieber

The OPP say they were called to the home of Jeremy Bieber, the pop singer's father, on Tuesday afternoon to deal with trespassers on the property in Ontario's Perth East township. (Steven D'Souza/CBC)

"This has regrettably resulted in charges of dangerous driving and assault. Mr. Bieber and Ms. Gomez have fully co-operated in the police investigation. We are hopeful that this matter will be quickly resolved."

Gloria Allred, a high-profile U.S. attorney, has indicated she is representing "two victims" in the incident.

"My clients will have no other comment at this time. All evidence has been provided to the Canadian authorities," she said in an email to The Canadian Press.

Allred did not indicate whether her clients were photographers.

Celebrity gossip website TMZ.com had published photos over the weekend of Bieber and Gomez, his on-again, off-again girlfriend, riding on an ATV near Stratford. The Township of Perth East is located nearby.

On Tuesday afternoon, the CBC's Steven D'Souza reported that two OPP officers had arrived at the home of Jeremy Bieber, the pop star’s father, in Perth East. Police said they were called there because of trespassers on the property.

Paparazzi problems

Bieber has had issues with photographers before, including last week when he was driving his Ferrari and was hit from behind.

The incident prompted him to tweet that "we should have learned from the death of Princess Diana," going on to say that while he doesn't "have a problem" with paparazzi, he believes that "when they act recklessly they put us all in danger."

JUSTIN BIEBER CHARGES

The pop star grew up in the Stratford area and rocketed to fame in his mid-teens. Bieber continues to tour and has more than 50 million followers on Twitter.

Every facet of Bieber's life draws intense media attention, leading to frequent stories about the pop star and the people in his life. From the time his grandparents were involved in a collision in his home province, to the drama surrounding his pet monkey, Bieber's name is never far from the headlines.

Bieber has faced numerous legal issues on both sides of the border lately.

With reports from the CBC's Steven D'Souza and The Associated Press