Singapore has launched an investigation after British trip-hop band Massive Attack displayed a Palestinian flag during a concert, police said Friday.

The city-state bans the public display of all foreign flags, national emblems or banners without a permit.

A video circulating online showed two band members on stage raising a Palestinian flag to loud, prolonged cheers from the audience.

The concert was held on Wednesday, according to local media.

Broadcaster CNA quoted one concertgoer as saying the band members shouted “free Palestine” during their performance and that many in the audience joined the chant.

The Singapore Police Force said in a statement to AFP that “reports were lodged and investigations are ongoing”, adding that the government’s media regulator was “also investigating a possible breach of licence conditions”.

The unpermitted display of a foreign flag is punishable with a fine of up to 500 Singapore dollars ($389), a maximum prison term of six months, or both.

The concert promoter did not immediately respond to AFP ’s request for comment.

The band is known for its criticism of Israel’s military actions in Gaza and has used its popularity to support the Palestinian cause.

In April, frontman Robert Del Naja was among more than 200 people arrested at a protest in London’s Trafalgar Square in support of Palestine Action, an activist group banned by British authorities.