Syria has told leaders of unofficial Kurdish parties that the state will no longer tolerate their activities.
Unrest gripped Kurdish areas in March
Military intelligence officials summoned three leaders to tell them the news on Wednesday, according to a statement by a human rights activist.
If they do not cease, they were told they would be treated as if they were members of other "banned" parties.
Syria's single-party rulers have freed political prisoners but still harshly repress any pro-democracy moves.
Human rights lawyer Anwar al-Bunni said Kurdish party leaders Faud Aliko, Aziz Daoud and Saleh Kado had been summoned by the secret police, but the warning applied to all 14 Kurdish parties.
Party leaders were told to wait until the government issued a law allowing parties to operate.
Mr Bunni's statement said that, by not having issued such a law until now until now, the authorities were intent on quashing political activity.
BBC correspondent Magdi Abdelhadi in Damascus says Syrian Kurds - who make up about 10% of the country's 17m people - complain of discrimination and demand the right to speak their language.
Kurdish unrest in March left about 30 dead and more than 100 injured when the security forces intervened after a riot at a football match.
Civil rights activists say several hundred Kurds are still in custody following the clashes in Qamishli in the north-east of the country.
Correspondents say the latest move is being seen as a major setback by Kurdish groups, as relations with the state appeared to be on the mend again.
Mr Aliko said his Yekiti party would continue activity regardless.
Kurds have long complained they lack basic rights
"If they want to arrest us, let them arrest us," he said in remarks quoted by Reuters.
"We did not set up political parties after a decision from the authorities and we will not disband them after a decision from the authorities."
There has been no word about the ban by Syrian officials.
In a separate case, a Syrian human rights group said some 20 students were still being held by the authorities several weeks after they had been arrested.
It is not clear what they are being held for, our correspondent says, but some reports suggest that they belong to a militant Islamic group.