BERLIN (AP) — A prominent British-Palestinian surgeon who volunteered in Gaza hospitals during the first weeks of the Israel-Hamas war said he was denied entry to Germany Friday to take part in a pro-Palestinian conference — an event that police later ended early.

Dr. Ghassan Abu Sitta said he arrived at Berlin airport on Friday morning before being stopped at passport control, where he was held for several hours and then told he had to return to the U.K.

Airport police said he was refused entry due to “the safety of the people at the conference and public order,” Abu Sitta told The Associated Press by phone. There was no immediate comment from German federal police.

Abu Sitta said his ban was to last until Sunday, covering the planned duration of the Berlin conference he was to attend, entitled the Palestine Congress. The gathering was to discuss a range of topics, including German arms shipments to Israel and solidarity with what organizers called the Palestinian struggle.