Several hundred people gathered in central London on Sunday to protest against the arrest of seven alleged members of the Kurdistan Workers' Party.
The group, known as the PKK, is outlawed by the UK government.
Many of the protesters held placards with “stop the attacks on Kurds” and “hands off our community centre” written on them.
The protesters – many wearing face coverings – blew whistles, chanted and played music as they made their way through the streets.
“To British people and Metropolitan Police, hands off Kurds,” one man said.
Their march followed a route from Trafalgar Square to Whitehall. The Metropolitan Police had warned those attending that expressing support for the proscribed group is a criminal offence.
At one point, officers moved in and circled a male protester, but appeared to merely take his details rather than arrest him.
The PKK wants an independent Kurdish state in south-east Turkey and has been banned in the UK since 2001.
Last week, seven people were arrested in London on suspicion of terrorism offences linked to the group.
Searches took place at the Kurdish community centre in Haringey, north London, among other locations. A protest took place on Thursday evening near Green Lanes and Stanhope Gardens, close to the community centre.
The Met said a man was arrested on suspicion of expressing support for a proscribed terrorist organisation related to chanting during the protest.
London is busier than usual this weekend as protests clash with Black Friday shopping and Winter Wonderland festivities.
“We understand the strength of feeling from the Kurdish community and want to take this opportunity to remind anyone taking part in the march that the PKK is proscribed by the UK government and expressing support for them is a criminal offence,” chief superintendent Joe McDonald, who is leading the policing operation, said.
