The protests rocking the Arab world this week have one thread uniting them: Al-Jazeera, the Qatar-based satellite channel whose aggressive coverage has helped propel insurgent emotions from one capital to the next.

Al-Jazeera has been hailed for helping enable the revolt in Tunisia with its galvanizing early reports, even as Western-aligned political factions in Lebanon and the West Bank attacked and burned the channel’s offices and vans this week, accusing it of incitement against them.

In many ways, it is Al-Jazeera’s moment — not only because of the role it has played but also because the channel has helped to shape a narrative of popular rage against oppressive U.S.-backed Arab governments (and against Israel) since its founding 15 years ago. That narrative has long been implicit in the channel’s heavy emphasis on Arab suffering and political crisis, its screaming-match talk shows, even its sensational news banners and swelling orchestral accompaniments.

"The notion that there is a common struggle across the Arab world is something Al-Jazeera helped create," said Marc Lynch, a professor of Middle East Studies at George Washington University who has written extensively on the Arab media. "They did not cause these events, but it’s almost impossible to imagine all this happening without Al-Jazeera."

Yet Al-Jazeera’s opaque loyalties and motives are as closely scrutinized as its reporting. It is accused of tailoring its coverage to support Hezbollah in Lebanon and Hamas in Gaza against their Lebanese and Palestinian rivals. Its reporter in Tunisia became a leading partisan in the uprising there. And critics speculate that the network bowed to the diplomatic interests of the Qatari emir, its patron, by initially playing down the protests in Egypt.

Not since the 2003 invasion of Iraq, when U.S. officials accused it of sympathy for Saddam Hussein and the insurgency that arose after his downfall, has Al-Jazeera been such a lightning rod. This time, its antagonists as well as its supporters are spread all over the Arab world.

This week, Mahmoud Abbas, the president of the Palestinian Authority, accused Al-Jazeera of distorting his positions, inciting violence and trying to destroy him politically. The station had broadcast a special report based on leaked documents that appeared to show Abbas and his allies offering Israel far-reaching concessions on Jerusalem and the fate of Palestinian refugees. The reporting set off angry demonstrations against the Palestinian Authority in Gaza, and in response, Abbas loyalists attacked Al-Jazeera’s office in Ramallah.

In Lebanon, Sunni supporters of the ousted prime minister, Saad Hariri, set fire to an Al-Jazeera van and menaced a crew in the northern city of Tripoli, accusing the channel of sympathizing with their Shiite opponents.

There is little doubt that Al-Jazeera takes sides in the Palestinian dispute, portraying Hamas more favorably than its rivals — and it is more open about Arab anger at Israel than some other outlets. Even the station’s fans concede that it has blind spots and political vulnerabilities.

On Tuesday afternoon, as the street protests in Egypt were heating up, Al-Jazeera was uncharacteristically slow to report them, airing a culture documentary, a sports show and more of its "Palestine Papers" coverage of the leaked documents.

Many Egyptians felt betrayed, and Facebook and Twitter were full of rumors about a deal between Qatar — the Persian Gulf emirate whose emir, Sheik Hamad bin Khalifa al-Thani, founded Al-Jazeera in 1996 — and President Hosni Mubarak of Egypt, who visited the emir in Doha last month. Within a day, Al-Jazeera was reporting from the streets in Cairo in its usual manic style.

Al-Jazeera’s freewheeling broadcasts have long made it the bete noire of Arab governments, and in some earlier instances they have succeeded in reining it in.

In 2007, the channel received orders to soften its blunt coverage of Saudi Arabia after Qatar and the Saudis mended a smoldering political feud. That remains a weak point for Al-Jazeera — as for most of the pan-Arab media, which are largely owned by Saudi Arabia.

For all its flaws, Al-Jazeera still operates with less constraint than almost any other Arab outlet and remains the most popular channel in the region. To many Arabs, Al-Jazeera’s recent expose on the Palestinian Authority documents — sometimes called "Pali-leaks" — is of a piece with its reporting on protests against autocratic Arab regimes.

The Palestinian Authority is widely seen as a pawn of Israel and the West, an institution with little popular support that is kept alive by force, much like those Arab dictators. If Al-Jazeera is often accused of institutional sympathy for Islamists, that is at least in part because Islamism has become the most powerful popular force in the region (although not, curiously enough, in the recent protests).

And Al-Jazeera has been widely admired for its aggressive coverage of the Tunisian uprising, which was largely ignored in most Western outlets. The channel succeeded despite serious obstacles: The Tunisian government had barred its reporters from the country, and a Tunisian born-anchor, Mohammed Krichen, arranged for an old friend, Lotfi Hajji, to work under cover as Al-Jazeera’s eyes and ears on the ground.

Hajji, a freelance journalist who also calls himself a human rights activist, was followed and harassed by the secret police almost constantly. After the uprising started, local contacts began sending Hajji amateur videos of police violence over Facebook. Al-Jazeera began showing the grainy cell phone videos on its broadcasts, as part of what the station sympathetically labeled "the Sidi Bouzid Uprising" after the town where a young man started it all by setting himself on fire Dec. 17.

Each time Al-Jazeera broadcast the videos, more would flood into Hajji’s Facebook account, in a cycle that blew the seeds of revolt across the country.

"During the era of Ben Ali a lot of journalists wouldn’t dare broadcast these images — like a video of a policeman beating a common citizen, because the police might come for them," Hajji said, speaking of Tunisia’s ousted president, Zine El Abidine Ben Ali. "But being a human rights activist pushed me to show what was really happening."

Two years ago, an amateur journalist reporting for a website was jailed for showing film of an uprising in the Tunisian city of Gafsa; with no coverage in Facebook or Al-Jazeera, it never spread to other towns.

As the protests accelerated this month, some Tunisian officials protested that Al-Jazeera was hyping the unrest because of its anti-Western agenda: its managers wanted to see a "moderate" Arab regime fall, even if the protesters were not Islamists, like those in so many earlier revolts. But that seems unlikely. Al-Jazeera’s producers knew they had a story line that their audience would love.

Since the fall of Ben Ali, Al-Jazeera’s reporters and producers have spoken with pride of their role in the events. They also recognize that their reputation as a catalyst carries risks.

"I think we should be careful — I mean we shouldn’t think that our role is to release the Arab people from oppression," said Krichen, the anchor.

"But I think we should also be careful not to avoid any popular movement. We should have our eyes open to capture any event that could be the start of the end of any dictator in the Arab world."

© 2011 The New York Times Company