Reports say live ammuntion is being used against protesters marching on the compound of Muammar Gaddafi, the Libyan leader.
The Libyan News Centre (LNC) based in Geneva, Switzerland, announced on Monday afternoon that Libyan security forces were killing protesters in Tripoli.
Ahmed Elgazir, a human rights researcher, said the LNC received a call for help from a woman "witnessing the massacre in progress who called on a satellite phone".
Phone lines in the country have been blocked, making it impossible to verify the information.
Source: Al Jazeera