A petition on the British government’s website to ban Donald Trump from the U.K. has gathered over half a million signatures, making it the most popular of its kind ever.

Under U.K. law, parliament is obliged to hold a debate on any such petition that gathers over 100,000 signatures. Somewhat ironically, the petition that had previously held the record for signatures was to “Stop all immigration and close the U.K. borders until ISIS is defeated.”

Trump has caused outrage, much of it sincere but at least some of it it politically calculated, with his comments about the U.K.’s problems with its 2.7 million-strong Muslim population. He said that parts of London were “so radicalized” that police officers were “afraid for their very lives” to go there. The comments had initially appeared to be just a sideswipe to his equally inflammatory comments about banning Muslims from entering the U.S., but have since taken on a life of their own.

Prime Minister David Cameron has called the comments “divisive, unhelpful and quite simply wrong,” while Scotland’s First Minister Nicola Sturgeon has revoked Trump’s status as a business ambassador for Scotland (Trump countered in a regional Scottish newspaper that she should have given him back the $300 million he’s investing in Scotland’s golf resorts before “pandering to political correctness.”)

In characteristic style, Trump responded to criticism of his remarks Thursday by ratcheting up the rhetoric, with this tweet.

Muslims in the U.K. account for around 4.5% of the total population, according to the last official census in 2011. The BBC, citing security sources, reports that at least 700 have traveled to Syria to fight for the so-called Islamic State, including the notorious Mohammed Emwazi, or “Jihadi John”, who figures in numerous videos of the execution of western hostages held by IS. Emwazee is believed to have been killed by a U.S. airstrike.