Saudi authorities repeatedly warned Germany about the man alleged to have carried out Friday’s attack on a Christmas market in the east German city of Magdeburg that left five dead and dozens injured, according to German security officials.

The officials said Riyadh warned the German authorities the suspected attacker, Taleb al-Abdulmohsen, a Saudi dissident who described himself as an ex-Muslim, had boasted on social media that “something big will happen in Germany”. It was unclear if police ever acted upon the warnings.

Al-Abdulmohsen’s many posts on social media site X reveal him as a fierce critic of Islam who railed against Muslim immigration into Europe and in recent months exhibited a growing hostility to the German authorities, whom he accused of trying to censor him.