Terrorist mastermind Osama bin Laden apparently has surfaced on an audiotape calling for the overthrow of Saudi Arabia's government.

The lengthy message criticizes the Saudi monarchy, saying its attempts at reform will not change anything and that change will only come through armed struggle and the government's overthrow.

Authorities say the authenticity of the tape, which surfaced Thursday on an Islamist website, could not immediately be verified.

He also praises the militants who attacked the U.S. consulate in the Saudi city of Jeddah earlier this month, asking God to be merciful on them. Four of the attackers were killed, a fifth was arrested. Five consulate staff members who were not American were also killed.

Osama bin Laden remains a fugitive. He was last heard from in a videotape shortly before the U.S. presidential elections last month.

Some information for this report provided by AP, AFP and Reuters.