LONDON — British Prime Minister Keir Starmer said Monday that a “standing army” of specialist police would be set up to deal with rioting and that the justice system would be ramped up to handle hundreds of arrests after violent disorder rocked cities across the nation over the past week.

Starmer convened an urgent meeting after lawlessness he blamed on “far-right thuggery” that was driven in part by misinformation on social media that whipped up anger over a stabbing rampage at a dance class that killed three girls and wounded 10 people. False rumors spread online that the suspect was a Muslim asylum-seeker led to attacks on immigrants and mosques.

“Whatever the apparent motivation, this is not protest. It is pure violence, and we will not tolerate attacks on mosques or our Muslim communities,” Starmer said. “The full force of the law will be visited on all those who are identified as having taken part in these activities.”

On Sunday, angry mobs attacked two hotels used to house asylum-seekers, breaking windows and lighting fires before police dispersed the crowds and residents were evacuated. Dozens of police officers have been hospitalized for injuries in the past six days, having been struck with bricks, bottles and large wooden posts.

More than 375 people have been arrested in the mayhem so far, the National Police Chiefs’ Council said, and more are expected.

Many made court appearances Monday and found themselves facing at least several weeks behind bars until their next hearings.

Starmer’s plan to beef up the criminal justice system and deliver quick justice faces significant challenges — courts are already backed up, and prisons are so overcrowded that plans were already in the works to release inmates early, said Cassia Rowland, a senior researcher at the Institute for Government think tank.

Starmer dismissed calls to use the army. His office said police can handle the disorder. Starmer also said social media companies have not done enough to prevent the spread of misinformation that has fueled far-right violence.