Egypt's decision on Sunday to close the offices of Al Jazeera illustrates the leading role the Arabic broadcaster has taken in reporting unprecedented popular revolts against Arab rulers.

Egypt has often harassed the Qatar-based channel since it started in 1996, setting off a revolution in Arab media in the face of state-controlled information, but it had never before tried to shut down its operations completely.

The channel led coverage of a Tunisian uprising that toppled Zine al-Abidine Ben Ali earlier this month, even though it was already banned from the North African country.

Then, sensing that Tunisia's example would set off copycat movements elsewhere, the channel charted mobilisation in Egypt that led to huge protests in the past week demanding the end of President Hosni Mubarak's rule.

"Al Jazeera saw the gravity of the situation (in Tunisia and Egypt)," said Shadi Hamid of Doha's Brookings Institute. "They saw it was going to be big before other people did and that it would stand as one of the historic moments in Arab history."

Arab governments have often closed the offices of the channel, which helped put tiny Gulf state Qatar on the map and boosted its status as a leader of regional diplomacy.

A major oil and gas power, Qatar employs vast resources to back the channel. This month it released a stack of secret documents revealing embarrassing Palestinian Authority concessions to Israel in peace talks.

A leaked U.S. diplomatic cable released by WikiLeaks in December said U.S. diplomats saw Al Jazeera as a "bargaining tool" used by Qatar in its foreign policy. Emad Gad of the Al Ahram Strategic and Political Studies Center said the effort to smother Al Jazeera was the last effort of a dying authoritarian system to control events in the traditional heavy-handed manner.