"We call on the Syrian authorities to reveal his fate and say where he is being detained," or if appropriate, "to try him in court."
The rights groups said they did not know why the 33-year-old student at Damascus university had been arrested.
They also highlighted "the multiplication of arbitrary arrests and the disappearance of numerous Syrian citizens, measures justified by the state of emergency in force in Syria since 1963."
The joint statement was signed by the London-based Syrian Observatory for Human Rights, the Syrian League for the Defence of Human Rights and the National Organisation of Human Rights in Syria.
Also on Wednesday the German government's human rights commissioner condemned the jailing of a 79-year-old prominent human rights lawyer by a Syrian court and demanded his immediate release.
Markus Loening said he was "shocked" by the sentencing of Haytham al-Maleh, who he described as a leader of the Syrian human rights movement, to three years in prison on Sunday on charges of "publishing false information."
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The rights groups said they did not know why the 33-year-old student at Damascus university had been arrested.
They also highlighted "the multiplication of arbitrary arrests and the disappearance of numerous Syrian citizens, measures justified by the state of emergency in force in Syria since 1963."
The joint statement was signed by the London-based Syrian Observatory for Human Rights, the Syrian League for the Defence of Human Rights and the National Organisation of Human Rights in Syria.
Also on Wednesday the German government's human rights commissioner condemned the jailing of a 79-year-old prominent human rights lawyer by a Syrian court and demanded his immediate release.
Markus Loening said he was "shocked" by the sentencing of Haytham al-Maleh, who he described as a leader of the Syrian human rights movement, to three years in prison on Sunday on charges of "publishing false information."
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