Three people have been arrested for spraying fake blood on the walls of the Ahoy exhibition centre in Rotterdam where a “defence and security” fair is currently taking place, news website Nu.nl reported on Thursday morning.

Around 100 demonstrators have gathered in groups outside the complex, and riot police are also on standby, Nu.nl said.

The aim of the fake blood protest, the campaigners say, is to “confront participants at the fair with the bloodshed they are responsible for all over the world”.

The fair is an annual event organised by the Dutch defence industry and includes 140 companies and organisations from all over the world, including several from Israel. Dutch telecoms firm KPN is there as the main sponsor.

KPN’s offices were also daubed with paint and fake blood last week in protest at their participation at the trade fair.

Every year there are protests outside the event, which is taking place for the 35^th time this year.