Anti-government activists in Libya have been using social networking sites to rally support for protests on what they are describing as a "day of anger".

There were reports of clashes in two cities late on Feb 16, with two people reported dead in the eastern city of Beyida. Dozens of people were injured in violent demonstrations on Tuesday night in the eastern city of Benghazi. The unrest there followed the detention of an outspoken government critic.

Witnesses say that at one stage up to 2,000 people were involved in the protests early in Benghazi, which saw a march on government offices in the city. The protesters are said to have thrown stones and petrol bombs, and set vehicles alight. Witnesses said police used rubber bullets and water cannon to disperse them.

The protests reportedly began after the arrest of Fathi Terbil, who represents relatives of more than 1,000 prisoners allegedly massacred by security forces in Tripoli's Abu Salim jail in 1996. He was later said to have been freed.

In a speech broadcast, Colonel Gaddafi made no mention of the unrest but said the "revolutionaries" would prevail.

"Down with the enemies, down with them everywhere; down with the puppets everywhere, the puppets are falling, the autumn leaves are falling!" Mr Gaddafi said. "The puppets of the USA, the puppets of Zionism are falling."

In a statement issued after the Benghazi clashes, a senior Libyan official warned that the authorities "will not allow a group of people to move around at night and play with the security of Libya".

More than 100 members of a banned Islamist militant group were freed from Abu Salim on Wednesday. It is not clear if the Benghazi clashes and the release of the inmates were connected, BBC reported.