Activists say more than 70 inmates have stopped eating in a bid to draw international attention to the inhuman prison conditions in Saudi Arabia.
They hope that their protest would prompt an immediate action to stop the gross violation of human rights in Saudi jails.
Saudi activists say there are more than 40,000 political prisoners, mostly prisoners of conscience, in jails across the kingdom.
According to the activists, most of the detained political prisoners are being held by the government without trial or legitimate charges.
Some of the detainees are reported to have been held without trial for more than 16 years. Attempting to incite the public against the ruling regime and the allegiance to foreign entities are usually the ready-made charges against political dissidents in Saudi Arabia.
Families and relatives of political prisoners have held several public gatherings in major cities, including Riyadh, Mecca, Medina and Buraidah. However, their protests have failed to bear any results.