Millions of Arabs across the Middle East and north Africa are watching vivid and often shocking coverage of the Israeli military onslaught on Hamas in the Gaza Strip on Arabic satellite TV channels, with al-Jazeera again leading the field.

Al-Jazeera, based in Qatar, has four correspondents in Gaza and its bulletins are broadcasting graphic images that would never find their way on to western TV screens. "It's very dangerous inside Gaza for our people, but they are trying to focus on humanitarian issues," said Ahmad Jaballah, the channel's deputy editor.

On Saturday, the first day of Israel's Operation Cast Lead, it broadcast live from Gaza City's Shifa hospital as the victims of the first bombing raids were being treated. Yesterday much of the footage was of funerals. Precise audience figures are hard to come by, but al-Jazeera claims it has a regular audience of 50 million, rising during a crisis of this magnitude. Anecdotal evidence suggests that from Yemen to Morocco it is easily beating its nearest satellite rivals, the Saudi-owned al-Arabiya and the BBC Arabic TV, launched this year.

Al-Jazeera pictures are now also available free on its YouTube site. Its sister English-language channel ensures they have a global reach, though the Arabic channel and website show the bloodiest pictures: one yesterday featured a dead Palestinian toddler over the caption: "Children of Gaza: for what sin were they killed?"

Al-Jazeera has also just become available to computer users live over broadband on the Livestation Network in every country except the US, where it is blocked.

The Gaza violence is being covered intensively by al-Manar, the TV station of Lebanon's militant Shia Hezbollah movement. Coverage elsewhere on Arab state-run TV channels reflects the views of individual governments, with Egypt, Jordan and Saudi Arabia openly critical of Hamas as well as Israel. Syria, Iran's only Arab ally, highlights Palestinian resistance.

In this febrile atmosphere, everything is intensely political: Hassan Nasrallah, Hezbollah's leader, this week attacked al-Arabiya by dubbing it "al-Ibriya," a pun suggesting it is serving Jewish interests.

Al-Jazeera, sensitive to charges of partisanship, has interviewed Israeli ministers and officials as well as the exiled Hamas leader Khaled Meshal in Damascus. But it has been unable to interview Ismail Haniyeh, the Hamas prime minister, who is presumably in hiding in Gaza. It has reported from Sderot and other Israeli towns hit by Palestinian rocket and mortar fire.

On Monday it interviewed Tzipi Livni, Israel's foreign minister and prime ministerial hopeful, who criticised the channel. But its coverage is controversial in the Arab world too. The western-backed Palestinian Authority has accused it of being biased in favour of Hamas.