Liam O'Hanna, whose stage name is Mo Chara, is alleged to have waved the flag of banned militant group Hezbollah during a Kneecap gig in London in November 2024.
The 27-year-old was charged in May under the Terrorism Act, under which it is a criminal offence to display an article in a way which arouses reasonable suspicion that someone is a supporter of a proscribed organisation.
Belfast-based Kneecap, who rap in Irish and English and regularly display pro-Palestinian messages during their gigs, previously said the flag had been thrown on stage and described the charge against O'Hanna as an attempt to silence them.
O'Hanna appeared at Westminster Magistrates Court where supporters, including some Northern Irish politicians and musicians including Paul Weller, massed before the hearing on Wednesday.
A group of musicians sang Irish ballads and many in the crowd waved Irish and Palestinian flags and held placards.
He had to push past a scrum of photographers when he arrived as supporters chanted "Free Palestine" and "Free Mo Chara".
Prosecutor Michael Bisgrove told the court the case was not about O'Hanna's support for Palestinians or his criticism of Israel, saying he was well within his rights to do that.
"The allegation in this case is a wholly different thing and deals with the video recording showing that, in November of last year, Mr O'Hanna wore and displayed the flag of Hezbollah ... while saying 'up Hamas, up Hezbollah'."
O'Hanna's lawyer Brenda Campbell said the defence would argue the charge was brought after the six-month limit to bring such a charge.Â
"If we are right in relation to that, then this court has no jurisdiction and there ends the case," she said.
A hearing will be held on August 20 to determine whether the charge was brought too late, Judge Paul Goldspring said.
O'Hanna spoke only in court to confirm his name, date of birth and address.
One of his lawyers, Darragh Mackin, told the crowd of supporters: "The more they come after Kneecap, the louder they will get."
