A synagogue in Belgium has been damaged in an explosion in what authorities have said was an "antisemitic" attack.

The explosion in the eastern city of Liege happened at around 4am local time, Belgian broadcaster VRT reported.

The blast blew out the windows of the synagogue and of a building on the opposite side of the road.

Pictures circulating online showed damage to the synagogue's wooden front door. No injuries were reported.

The incident was an "extremely violent act of antisemitism", Liege's mayor Willy Demeyer told RTBF.

He added it was "unacceptable for conflicts to be imported from outside into our city", referring to US-Israeli strikes on Iran.

Police have not given a cause for the explosion, but Mr Demeyer said the blast "involved a device, so it was all intentional and targeted", without giving further details.

Belgium's interior minister Bernard Quintin said it was "a despicable antisemitic act that directly ‌targeted the Jewish community".

He added "security measures around similar sites will continue to be strengthened".

Read more from Sky News:
Four arrested on suspicion of spying on Jewish community
More antisemitic incidents after Manchester synagogue attack

Yves Oschinsky, president of the Committee of Jewish Organisations of Belgium, told RTBF the incident was "extremely worrying, serious and concerning".

Police have cordoned off the street while specialist officers from the counter-terrorism unit investigate the explosion.