Rioting Erupts Over British Poll Tax : Protest: ‘Marxist agitators and militants’ are blamed for violent street battles. Police arrest 340 people, and more than 130 are hurt.

A huge demonstration against a highly unpopular new tax scheme turned into one of the worst riots to ravage central London in memory Saturday as militants torched cars, smashed windows, looted stores and attacked police in more than six hours of almost nonstop violence.

At least 340 people were arrested and more than 130 were injured, including at least 58 police officers, as some of this city’s most famous landmarks became the focus of running battles that left streets and sidewalks littered with broken glass, shattered paving stones and upended trash containers.

The violence moved from the front of Prime Minister Margaret Thatcher’s official residence at No. 10 Downing St. through Whitehall and Trafalgar Square to the West End theater district, where one show was canceled and the audience at another was locked in to protect it from the riot outside.

At least two buildings were set ablaze, including the South African Embassy, and authorities closed subway stations in the area of Leicester Square, an entertainment mecca that is normally considered London’s busiest district on a Saturday night.

“It was a well-organized demonstration, but these lunatics, anarchists and other extremists, principally from the Socialist Workers’ Party, were out for a rumble the whole time,” said a distressed George Galloway, a member of Parliament from the opposition Labor Party.

“If they didn’t exist, the Tories would need to invent them,” he added, referring to the discredit the militants brought to the campaign against the controversial tax scheme devised by Thatcher’s ruling Conservative Party.

The new community service charge, or poll tax, as it is more popularly known, replaces the old system of property taxes to pay for local government services with a flat levy on everyone over age 18.

The new tax goes into effect today in England and Wales. It is seen as a key factor behind a precipitous drop in popularity that has left the Conservatives trailing Labor badly in the polls.

Thatcher, who was in the resort town of Cheltenham on Saturday to address a meeting of her party’s activists, defended the poll tax and blamed the violent demonstrations on “Marxist agitators and militants.”

There was also trouble in Cheltenham after Thatcher spoke, when protesters pelted police outside the hall with rocks and other debris. Two police officers were reported hurt, and 48 people were arrested there.

There was also a peaceful anti-poll tax demonstration involving a reported 25,000 people Saturday in Glasgow. The controversial levy has already been in force for a year in Scotland.

Deputy Assistant Police Commissioner David Meynell told reporters that the London demonstration also began as a responsible and peaceful march of more than 40,000 people on a warm, sunny day. But their actions were soon “completely overshadowed” by as many as 3,000 hooligans whom police described as “fairly hard-core, violent people,” many of whom had been drinking.

The trouble began about 3 p.m., when police tried to prevent a breakaway group of demonstrators from carrying their protest down Whitehall toward Thatcher’s official residence.

Some witnesses asserted that overzealous police crowd-control tactics triggered the violence. But others, including some of the demonstration’s organizers, said that a “minority of extremists” appeared determined to cause trouble from the beginning.

Police in riot gear pummeled aggressive young protesters with billy clubs, while the militants fought back with fists, rocks and sticks.