Pakistan's private television channels beamed dramatic images of security forces surrounding the Supreme Court and arresting critics of beleaguered President Pervez Musharraf [Images] for almost three hours after the imposition of emergency before they were finally taken off the air.

The channels were the first media outlets to flash the news about the military ruler's decision to impose emergency after a series of meetings with close aides.

As more details came in, all the news channels interrupted their regular programming to provide updates about the emerging situation.

Dawn News, one of the newest channels and the first news channel in English, and Geo News beamed footage of troops surrounding the Supreme Court and other key buildings along the Constitution Avenue, the tree-lined boulevard in the heart of the national capital.

The channels hastily arranged discussions with legal and constitutional experts to analyse the developments and critics of Musharraf like Supreme Court Bar Association Aitzaz Ahsan appeared on them to speak out against the emergency.

Ahsan, the counsel for one of the petitioners opposing Musharraf's re-election in uniform and a key figure in the legal fraternity's opposition to the military ruler, was arrested minutes after he finished addressing a news conference that was aired live by most channels.

Though the freedom of the press was suspended with the imposition of emergency at about 6.15 pm (local time) and the news channels were reportedly issued orders to stop their broadcasts, they remained on air for almost three more hours before they were finally yanked off the airwaves.

Pakistan has witnessed a proliferation of news channels in the eight years that Musharraf has been in power, and they have played a key role in reporting the latest developments in a country where the airwaves were till recently dominated by state-run PTV and entertainment channels, including some from India.

Observers noted that the reports aired in recent days by the news channels of the fighting between government troops and pro-Taliban militants in the Swat valley had exposed the extent to which the authority of Musharraf's military regime had been undermined in the restive tribal areas bordering Afghanistan.

Saturday's black out of the news channels is not a new phenomenon -- they have also been taken off the air on several recent occasions. Most channels were blacked out after police used force to disperse a protest by lawyers and civil society groups outside the apex court on September 29.