Twenty squatters were arrested in raids across London today ahead of the royal wedding, police said. Officers swooped on three addresses as part of an intelligence-led operation, taking the suspects into custody at various London police stations.
One lawmaker described the raids as "some form of pre-emptive strike".
Scotland Yard has more than 5,000 officers on duty for Friday's wedding and has pledged to take "robust" action against anyone threatening to disrupt the occasion.
Police sources said the raids were made as part of investigations into recent outbreaks of disorder in central London, including student and anarchist riots.
"These arrests are part of ongoing proactive work to tackle suspected criminality," a Scotland Yard spokesman said. "They are not specifically related to the royal wedding but have been brought forward ahead of the event." Nineteen people were arrested for stealing electricity at an address in Camberwell, south London, and one person was arrested in Hackney, east London, in connection with a riot on March 26.
An address in the village of Sipson, next to London's main Heathrow Airport, was also raided but there were no arrests.
Lawmaker John McDonnell, whose constituency includes Sipson, said in parliament that the raids appeared to be "some form of pre-emptive strike before the royal wedding".
Joe Rake, 20, a Sipson squatter, said he woke up to some 40 officers raiding the property.
"It seems obvious to us that they thought we were going to do something at the wedding," he said. "They searched through our things but took nothing away and made no arrests." Police are imposing a tight security clampdown around the wedding of Prince William and Kate Middleton.
Snipers will take to rooftops and undercover officers will mingle among the crowds as part of a massive covert and overt operation.
Security against potential threats from Islamist extremists, dissident Irish republican terrorists, anarchists and even lone stalkers is being balanced with the desire to let onlookers enjoy the pageantry.
Officers have been scouring central London for explosives and hidden weapons in recent days, inspecting drains, lamp-posts and traffic lights.