There have been reports of clashes between police and anti-government demonstrators in at least two Libyan cities.
The Al Jazeera news network reports at least two people have died during violent demonstrations in the eastern city of Bayda and there has been another protest in Benghazi.
Activists have been using social networking sites to rally support for mass protests planned later on Thursday, which they are describing as a "day of anger".
Earlier this week, dozens of people were injured in violent demonstrations in Benghazi. The unrest there followed the detention of an outspoken government critic.
Pro-democracy protests have recently swept through several Arab nations with the presidents of Tunisia and Egypt forced to resign amid growing unrest.