Singapore authorities are investigating Massive Attack after the British band reportedly expressed pro-Palestinian sentiments during a performance in the city-state.

According to local media reports and eyewitness accounts on social media, two members of Massive Attack held up a Palestinian flag at the show on Wednesday, and reportedly shouted "Free Palestine", with some in the audience joining them.

The BBC has contacted the organisers of the Singapore show and Massive Attack's management company for comment. Neither have responded yet.

Singapore has strict rules on public speech and what it deems as demonstrations, arguing that it is necessary to regulate them to protect social harmony.

Authorities have previously investigated public events related to the Israel-Gaza war. Earlier this year they fined several people for organising an unauthorised walk in support of the Palestinian cause.

In response to BBC queries on Friday, a spokesperson for the police and the media authority said that "reports were lodged and investigations are ongoing".

The spokesperson also said that the media authority is investigating a possible breach of licence conditions. Performances in Singapore, including concerts, usually require a permit.

The BBC has asked Singapore authorities whether the band members or anyone involved in the production of the show have been detained or barred from leaving Singapore pending investigations. Authorities have yet to respond.

Massive Attack is currently on a world tour, with Wednesday's performance their only date in Singapore. Their next show is due to be held in Seoul on Saturday.

The band, which pioneered the trip-hop genre, has long been known for its openly political stance on a number of issues, including the war in Gaza.

Massive Attack's frontman Robert Del Naja was arrested earlier this year when he took part in a demonstration in London. He was accused of showing support for Palestine Action, which is a proscribed organisation in the UK.

It is not yet clear what charges the band could face.

Singapore does not allow the public display of foreign national emblems, such as flags, without a permit or exemption.

Those found guilty could be fined up to 500 Singapore dollars (£290; $390), jailed for up to six months, or face both penalties.

Singapore has also taken a strong stance on public expressions of sentiment regarding the Israel-Gaza war.

Authorities in the multicultural country insist that this is necessary to preserve racial and social harmony.

In 2023 the home affairs ministry put out a statement, external advising against "the public display and wearing of articles" in relation to the Israel-Gaza war, including foreign national emblems.

"We must not let events happening externally affect this peace and harmony we have in Singapore," it said at the time.

Singapore police have also launched investigations into offline and online events, and have effectively banned public gatherings related to the war.

The Singapore government has consistently supported the "two-state solution", which would see a Palestinian state exist alongside Israel, as well as full Palestinian membership of the United Nations.