Just 48 hours ahead of massive nationwide protests in the United Kingdom against U.S. President Donald Trump's official visit on Friday, more than a dozen organizers and members of parliament accused the British police of "curtailing the right to protest and putting the health and safety of demonstrators in jeopardy" by denying groups permission to set up a stage and sound system at the main protest assembly point in London.

"This arbitrary cancellation by the police can only mean some of the many voices speaking out against Trump will be denied a platform."

—U.K. protest organizers

"Friday will witness one of the biggest and most vibrant demonstrations in recent British history," the organizers and lawmakers declared in an open letter on Wednesday. "While it is reasonable for the police to put in place measures for safety, it would be unprecedented for such a major demonstration to be denied permission for a stage."

"Having stages and speakers is a vital part of the right to public assembly—it provides the political content for rallies and processions, and means that organizers have a means to communicate with attendees," the letter adds.

The police have suddenly withdrawn permission for us to have a stage and sound system at Friday’s demonstration. Tweet @metpoliceuk and tell them this is wrong and to reverse their decision immediately. — Stand UpToTrump (@StandUp2TrumpUK) July 11, 2018

As Common Dreams reported on Monday, civil liberties groups have raised concerns that British police would attempt to illegally clamp down on the right to protest in an effort to "appease" the notoriously thin-skinned Trump.

Organizers are concerned that by refusing to grant groups permission to use a stage, the British government is attempting to "gag protesters."

"Not having a stage at the starting point is likely to seriously impede the ability of organizers to direct the crowds. This is a major safety concern given the high turnout and the fact that there are two marches taking place on the day, which will require complex stewarding arrangements. This arbitrary cancellation by the police can only mean some of the many voices speaking out against Trump will be denied a platform. We urge you to do everything in your power to remedy this situation."

Read the organizers' full statement: