The Syrian authorities detained prominent human rights activist Khalil al-Maatouq while he was on his way to work in the capital on Tuesday, his rights group said in a statement.
"Members of the security forces this morning arrested fellow lawyer Khalil al-Maatouq, executive director of the centre," said the Syrian Centre for Legal Studies and Research.
The centre condemned the arrest, describing it as "a clear message to peaceful activists who defend human rights, and to lawyers who defend prisoners of conscience." The group said Maatouq requires medical care for a serious lung problem and recently returned from treatment abroad.
"The nature of the regime's objectives and methods are clear," it said.
Thousands of people have been detained in Syria since the outbreak of a revolt against President Bashar al-Assad in March last year, many of them without charge, human rights groups say.