UK police on Monday said they were investigating a knife attack on a woman in a London park, with online footage showing she was wearing a T-shirt with a cartoon from Charlie Hebdo, the French magazine targeted by jihadists.
The 39-year-old woman was treated in hospital for a minor slash injury after the attack on Sunday afternoon at Speakers Corner' in Hyde Park, the Metropolitan Police said.
Footage posted on YouTube showed a man in a hooded top approach a woman holding an umbrella and stab her, apparently several times.
The man then takes off his hood and leaves.
The woman's T-shirt has the Charlie Hebdo logo and a cartoon showing a Muslim man kissing a cartoonist with the slogan "L'amour plus fort que la haine" (love is stronger than hate).
She has blood running down her face and shortly afterwards collapses to the ground.
Speakers' Corner is a historic place for open-air debate where people are allowed to make speeches on any lawful subject.
Police did not identify the victim by name but social media said she was Hatun Tash, a preacher from a group called DCCI Ministries that says it seeks to preach the Christian Gospel to Muslims.
Detectives said they had recovered a knife at the scene and the victim gave an account of what happened.
"We know that this assault was witnessed by a number of people, many of whom captured it on their phones. I would ask them, if they have not already done so, to contact police," said Detective Superintendent Alex Bingley.
Bingley asked people not to "speculate on the motive for the attack until we have established the full facts".
Twelve members of staff at the satirical weekly Charlie Hebdo were gunned down in January 2015 by two brothers who vowed allegiance to Al-Qaeda.
The gunmen said they were taking revenge for the magazine's publication of cartoons of the Prophet Mohammed that many Muslims find offensive.