A petrol bomb attack on Alliance's east Belfast offices has been branded an 'attack on democracy' by the party's MP Naomi Long.
Party colleague, Justice Minister David Ford also condemned the attack, in which two petrol bomb were thrown at the property in the Upper Newtownards Road in the city at about 10.45pm on Saturday night.
The PSNI said one of the petrol bombs ignited on the street and was extinguished by a passing police patrol.
They are looking for a man who was wearing a red-coloured hooded top who is believed to have been involved in the incident.
The suspect was seen making off in the direction of Finvoy Street.
Detectives have appealed for information.
Naomi Long MP said the petrol-bomb attack on the Alliance Party premises was an attack on democracy.
"This is not an attack on an individual party or office, it is an attack on democracy," she said.
"There can be no justification for this and there is no place for this kind of violence on our streets."
Justice Minister David Ford said the "attempt to petrol bomb the Alliance party office in East Belfast is a further attack on those who have a democratic mandate given by the people, unlike those behind all these incidents".
"They need to realise that the community right across Northern Ireland has decided that the future lies in peace and living together, not conflict," he said.