Organisers of the Eurovision Song Contest said they "regret" the opening act wearing a keffiyeh during his performance.
Eric Saade, a former Swedish contestant was not competing but performed a song on Tuesday, wearing a keffiyeh which has come to symbolise Palestinian resilience and a show of solidarity with the cause.
Saade, whose father is of Palestinian origin, has previously expressed support for Palestinians suffering under Israeli occupation and war on Gaza.
Last month he questioned criticism of wearing the keffiyeh and other symbols of Palestinian pride in an Instagram post.
"When you can no longer wear a symbol of your ethnicity in our so-called 'free world' it's even more important for me to participate," he wrote.
A spokesperson for the European Broadcasting Union (EBU) criticised his decision to wear the keffiyeh.
"The Eurovision Song Contest is a live TV show. All performers are made aware of the rules of the contest, and we regret that Eric Saade chose to compromise the non-political nature of the event," she said.
Ahead of the event held at the Malmo Arena, fans were warned by organisers not to bring any political symbols or flags, as pro-Palestine protests were expected.
Security also informed people that there would be "vigorous security checks".
The head of Israel’s Shin Bet security agency also led a delegation to Malmo last week to coordinate security arrangements for Israel’s participants, local media reported.
Israel's contestant, Eden Golan, was accompanied by a heavy security presence and is skipping most events during the festival, aside from live shows and rehearsals, amid protests and calls for Israel's expulsion due to the war on Gaza.
Another contestant, Ireland's Bambie Thug, was ordered by the EBU to change the pro-Palestinian markings on their face and legs during their performance on Tuesday.
Written in Ogham, an ancient Irish alphabet, the markings translated to "ceasefire" and "there is no freedom until Palestine is free".
The Cork-born performer was the first Irish act to qualify for the grand final since 2018.
They later clarified that they were ordered to change the messages, but added they felt it was important to be "pro-justice" and "pro-peace".
Calls for boycott
Fans have been calling for a boycott of the competition or a ban on Israel taking part this year, as Israel continues with its deadly and indiscriminate attacks on the Gaza Strip.
Israeli forces have killed at least 34,700 Palestinians, mostly women and children, since 7 October and wounded over 78,000. The bombing campaign has wreaked havoc on the besieged enclave and plunged it into a deep humanitarian crisis.
However, last December, organisers of the competition maintained that it remains a "non-political event", rejecting any calls for a boycott.
Last week, organisers of Eurovision said they reserve the right to remove any Palestinian flags or symbols, while spectators could only display the flags of the 37 participating countries, including Israel, as well as banners representing the LGBTQ community.
Swedish police have warned of tight security at the event, with authorities promising "visible" measures, including police armed with submachine guns and reinforcements from Denmark and Norway
While Israel is not in Europe, they are eligible to compete because its broadcaster is a member of the European Broadcasting Union.