Clare Farrell, co-founder of the environmental action group Extinction Rebellion, claimed she was barred from entering a show at London fashion week two days after helping to organise a protest against the British Fashion Council to highlight the industry’s role in fuelling climate change.

About 150 people from Extinction Rebellion formed human roadblocks and brought traffic to a standstill outside event venues on Sunday to cause disruption and urge the industry body to declare a climate emergency.

Farrell, who is also a spokeswoman for the direct action group, said she was approached by a police officer who addressed her by name when she was in the queue for the Bethany Williams show at 180 The Strand, London, on Tuesday afternoon, and was told she was not allowed to enter.

“The police liaison officer said I could queue up but that the venue wouldn’t let me in,” Farrell said. “She referenced Extinction Rebellion and pointed to a badge I was wearing.”

Farrell, a fashion designer, said that she had helped produce Williams’ line, which is dedicated to social justice and sustainability, and that she had not been intending to protest at the event.

“To exclude a designer who was both involved in the production of the line and working to bring attention to the climate and ecological crises from the show is just unbelievable,” she added.

The group said Farrell had a ticket for the show, and that staff at the venue were informed of her multiple roles in the production of Williams’ award-winning line. Williams was awarded the Queen Elizabeth II design award for her work, which addresses environmental issues, by the Duchess of Cornwall on Tuesday night.

A spokesperson for the Metropolitan police said: “On Tuesday 19 February, the organisers of a private event taking place on The Strand in central London took a decision not to admit a member of the public to their event. This decision was conveyed to the member of the public by a police officer at the scene.”

On Sunday, the British Fashion Council said that it was “pleased that we live in a country where we have a right to protest peacefully”.

It said in a statement: “We believe that more than any other capital, London has an opportunity to be a part of a cultural change around sustainable business practices that put creative product at their core.

“This week we hope to both encourage the showcasing of these creative businesses whilst increasing the dialogue around mindful consumerism, one that we are raising ourselves through our Positive Fashion programme.”

The British Fashion Council has been contacted for further comment.