Thousands of Britons rioted into the early hours Monday against plans to give UK police new powers to crackdown on protests — leaving 20 cops injured, including one with a punctured lung, officials said.

At least 5,000 people initially joined afternoon protests in Bristol against the planned legislation, BristolLive said, with many carrying placards that condemned a feared “police state” and “dictatorship.”

The so-called “Kill the Bill” protests then turned violent when “several thousand” people descended on a police precinct in the southwest England city — sparking a fiery riot raged for hours, the local outlet said.

After rioters attempted to push over a police van, officers were caught on two fronts, the outlet said — with police vehicles also getting torched and the precinct’s windows smashed. Some in the mob even managed to get onto the station’s roof and throw rocks at officers, BristolLive said.

Local police called in reinforcements from surrounding areas and used pepper spray and police dogs to push back against the rioters, the outlet said.

The violence left 20 officers injured. Two were hospitalized with broken bones, including one who also suffered a punctured lung, Avon and Somerset Police said.

The protests were against the government’s Police, Crime, Sentencing and Courts Bill — currently going through parliament — that would give police new powers to impose time and noise limits on street protests. The name of the protest, “Kill the Bill,” also has ominous undertones as UK police are commonly nicknamed “the Bill.”

While only seven people were arrested during the night, the force launched “one of the biggest appeals for wanted suspects that we’ve ever done,” Chief Constable Andy Marsh said.

“The wanton violence and destruction had nothing to do with protest – it was committed by those looking for an excuse to commit disorder,” the top cop said in a statement, condemning the “shameful” scenes.

“Officers were pelted with stones and missiles and fireworks and it was a terrifying situation for them to deal with,” he said. At least 12 police vehicles were wrecked after the protest was “hijacked by extremists,” he said.

The UK’s Home Secretary Priti Patel also ripped the “unacceptable scenes.”

“Thuggery and disorder by a minority will never be tolerated,” she tweeted.

Sue Mountstevens, police and crime commissioner for the Avon and Somerset region, called the riots “disgraceful and outrageous.”

“Police officers went to work yesterday and some have returned home via hospital battered and bruised,” she said.

Bristol Mayor Marvin Rees — who opposes the new legislation — told “Good Morning Britain” on Monday that the rioters were just using it as an excuse to “smash our city,” and had actually harmed their cause.

“It will be used as evidence by people who want to support the bill,” he said.

With Post Wires