In a statement issued Sunday, nine local rights group said Ghassan Al-Najjar was moved from the Central Damascus Prison to a government hospital for treatment after going on hunger strike.

Al-Najjar leads a small group called the Islamic Democratic Current. He is in his mid-70s.

He was arrested at his home in the northern city of Aleppo for urging Syrians to demonstrate against the government.

The groups urged the authorities to release him immediately.

There was no official comment on Al-Najjar's detention. An online campaign calling for protests on Feb. 5 fell flat when no protesters showed up in Damascus.