A small but noisy group of Kurdish protesters gathered outside the Old Bailey in London on Wednesday to protest at terrorism charges brought against a British teenager.

Shilan Ozcelik , an 18-year-old of Kurdish descent, was arrested earlier this year at Stansted airport.

She is believed to be the first British citizen to be arrested for allegedly trying to join the campaign against Islamic State in eastern Syria and western Iraq.

Outside the pre-trial hearing on Wednesday, Ozcelik’s supporters held up banners and could be heard chanting outside the court. She was refused bail and will remain in Holloway prison until a full hearing on 7 September.

Ozcelik, from Holloway, north London, faces one charge of engaging in conduct in preparation for giving effect to an intention to commit acts of terrorism under the 2006 Terrorism Act.

It is understood that the charges against Ozcelik relate to the Kurdistan Workers’ party (PKK), which is outlawed in Britain and has been locked in a separatist conflict with the Turkish army for decades.

Speaking outside the court, Mark Campbell, one of the organisers of the protest, said the teenager’s arrest had come at a time when Kurdish efforts to repel Isis were gaining widespread international support.

Neither the YPJ, the main women’s Kurdish militia in northern Syria, nor the YPG, the men’s militia, are listed as terrorist organisations. Supporters say the militias “have received praise from activists and senior politicians alike for their incredible efforts fighting back Isis from Kobane and parts of northern Syria and Iraq”.

Outside the court, around two dozen protesters held up placards calling for Ozcelik to be released, with slogans including: “We are all YPJ” and: “Shilan Ozcelik is not a threat to UK national security, Isis is”.

A statement issued by Peace in Kurdistan said: “The YPG and YPJ, who had been in a tacit alliance with US and British forces in the struggle for Kobane, are not listed on any terrorist list.”

Ozcelik was arrested on 16 January as she returned to the UK from Brussels.