Singapore police have launched an investigation into British band Massive Attack over a "possible breach of license conditions” after the group displayed a Palestinian flag at the end of its performance Wednesday.

Police said reports had been filed and investigations were ongoing, according to The Straits Times.

Singapore prohibits the public display of foreign national emblems without a permit or exemption. Offenders may face a fine of up to $500, up to six months in jail, or both.

Concert promoter Lushington said it was aware of the reports concerning the Massive Attack concert and would fully cooperate with the relevant authorities.

It added that the performance was the band’s only scheduled show in Singapore during its current tour.

Videos from the concert posted online showed two band members holding a Palestinian flag on stage as audience members chanted "Free Palestine.”