WIMBLEDON, England (AP) — Four activists wearing “Where is Peng Shuai?” T-shirts were stopped by security at Wimbledon on Monday and had their bags searched.

Peng is a retired professional tennis player from China who last year accused a former high-ranking member of the country’s ruling Communist Party of sexual assault. She has made very few public appearances since then.

similar episode happened to someone wearing a T-shirt supporting Peng at this year’s Australian Open. A spectator in Melbourne was removed from the grounds, but the tournament later reversed its decision and allowed people to wear the clothing as long as they didn’t congregate in large groups or cause problems for other spectators.

Jason Leith of the Free Tibet organization said he and his three colleagues put on the white T-shirts after entering the grounds of the All England Club on Monday.

“We didn’t have these on when we came in because we worried about not being let in. So we put them on and we were just walking around and a few people wanted selfies with us, so we were taking pictures with people,” said Leith, who is British.

Security arrived a short time later when the four men were walking under the big screen at the base of Henman Hill, Leith said.

“(They) started asking, ‘Are you planning to do any direct protesting? Are you planning on disrupting things?’” Leith said. “And then they asked, ‘Oh, do you mind coming over here so we can search your bags?’

“So then they started going through our bags. I guess they were looking for flags. They were looking for anything that might be used in any other form of protest.”

The men were allowed to remain at the grass-court Grand Slam and keep wearing the shirts but were asked not to approach any other spectators to talk about Peng, Leith said.

“That’s a bit strange. Why aren’t we allowed to talk to people?” said Leith, the head of income and engagement at Free Tibet.

Wimbledon organizers said the activists were welcome to stay on site.

All England Club CEO Sally Bolton said on Day 1 of the tournament that a spectator with a shirt mentioning Peng would be allowed to attend.

“We do have ground entry rules, and those ground entry rules are really focused on everyone’s quiet enjoyment of the tennis,” Bolton said. “So that’s not about what people are wearing; it’s about the way people behave.”

Peng disappeared from public view last year after accusing former Communist Party official Zhang Gaoli of sexual assault. Her accusation was quickly scrubbed from the internet, and discussion of it remains heavily censored.

Peng won two Grand Slam women’s doubles titles in her career, including at Wimbledon in 2013.

The women’s professional tennis tour canceled its tournaments in China because of the situation surrounding Peng.

Last year, Leith was arrested in Greece for disrupting the Olympic flame ceremony. The flame was headed for China ahead of this year’s Winter Olympics in Beijing.