Al-Marjeh square in central Damascus
His conviction "sends a clear message to the world: Syria will not tolerate peaceful forms of freedom of expression," Toner said in a statement.
"We call on the Syrian government to meet its responsibilities under the International Covenant on Civil and Political Rights," he said.
The sharp US criticism comes even as President Barack Obama's administration tries to engage diplomatically with its former foe as part of efforts to promote comprehensive Arab-Israeli peace.
"Syria should demonstrate its commitment to international legal norms by releasing Hassani and other Syrian citizens," Toner said.
He also called for the release of Haitham al-Maleh and Ali Abdullah, who he said "have been imprisoned solely for seeking to exercise their internationally recognized political freedoms."
Maleh was arrested in October and charged with "disseminating false information that could weaken national sentiment" in interviews and articles he published.
Maleh, who has worked with Amnesty International since 1989 and was involved in the creation of a human rights organisation in Syria, was arrested in 1980 and held for six years for calling for constitutional reform.
Abdullah, a writer who has served out a jail term for calling for democratic reforms, is to remain behind bars to face new charges, a human rights organisation said on Sunday.
Abdullah was one of 12 opposition figures who signed a "Damascus Declaration" calling for democratic change in Syria. They were convicted to jail terms in October 2008.
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"We call on the Syrian government to meet its responsibilities under the International Covenant on Civil and Political Rights," he said.
The sharp US criticism comes even as President Barack Obama's administration tries to engage diplomatically with its former foe as part of efforts to promote comprehensive Arab-Israeli peace.
"Syria should demonstrate its commitment to international legal norms by releasing Hassani and other Syrian citizens," Toner said.
He also called for the release of Haitham al-Maleh and Ali Abdullah, who he said "have been imprisoned solely for seeking to exercise their internationally recognized political freedoms."
Maleh was arrested in October and charged with "disseminating false information that could weaken national sentiment" in interviews and articles he published.
Maleh, who has worked with Amnesty International since 1989 and was involved in the creation of a human rights organisation in Syria, was arrested in 1980 and held for six years for calling for constitutional reform.
Abdullah, a writer who has served out a jail term for calling for democratic reforms, is to remain behind bars to face new charges, a human rights organisation said on Sunday.
Abdullah was one of 12 opposition figures who signed a "Damascus Declaration" calling for democratic change in Syria. They were convicted to jail terms in October 2008.
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