A traveling group of Paris Saint-Germain supporters was denied access to Thursday's UEFA Women's Champions League match at Chelsea's Kingsmeadow ground in London, where police confirmed that weapons and drugs were discovered on the bus.
Metropolitan Police received reports earlier in the day of supporters "causing criminal damage" outside the venue where Chelsea hosted the first leg of the Women's Champions League quarterfinals.
Officers were unable to locate those responsible for damaging parts of the ground. The police also received reports of additional disorder later in the day before confronting the group and conducting a search of their bus when they arrived at the stadium.
"Weapons, including knives and knuckledusters, were recovered along with Class A drugs," the Metropolitan Police said in a statement.
"One man from the coach was arrested for possession of Class A drugs and the remaining passengers were escorted from the area by police."
It's believed that up to 50 supporters - who did not have tickets to attend the match - were sent back to France, according to BBC Sport.
A door at the stadium was apparently damaged while parts of the venue were covered in "PSG" graffiti.
The group has previously been banned from attending PSG men's and youth matches but has yet to be barred from attending women's games, according to Jacqui Oatley of BBC Sport.
Chelsea secured a 2-0 victory ahead of next week's second leg in Paris.