LONDON: London police braced for their busiest day in years on Saturday, when tens of thousands of protesters were expected to attend the latest rally staged by far-right activist Tommy Robinson.

The British capital’s Metropolitan Police said it would deploy 4,000 officers — alongside horses, dogs, drones and helicopters — to manage the march and a counter-demonstration merged with a pro-Palestinian protest, as well as the FA Cup final.

The Met has imposed various conditions on the two rallies, over their routes and timings, in a bid to keep rival attendees apart.

The force, which estimates the operation will cost £4.5 million ($6 million), warned in a statement that it would adopt “a zero-tolerance approach.”

That includes for the first time making organizers legally responsible for ensuring invited speakers do not break hate speech laws.