Two motorbikes in Theresa May's convoy were involved in a crash with a car during her visit to France and Belgium to mark Armistice Day, according to local media.
The Prime Minister was in a convoy with Belgian prime minister Charles Michel when the collision occurred on Friday.
Two police motorcycles were knocked over in the incident, Belgian media reported.
The two motorcyclists, who were escorting Mrs May and Mr Michel after they laid wreaths at World War One British graves, were taken to hospital.
No one else was injured, according to La Libre Belgique newspaper.
De Standaard quoted Belgian premier Michel's spokesman describing the incident as an "unfortunate accident".
Mrs May was in Belgium to mark Sunday's centenary of the end of the 1914-18 war and later travelled for further ceremonies in France.
