Al-Qaeda's deputy leader has mocked US President George W Bush's plan to increase Iraq troop numbers in a video message, according to a US website.
Al-Zawahri is second in line to al-Qaeda leader Osama Bin Laden
In the tape, apparently intercepted by US-based terrorism think tank Site, Ayman al-Zawahiri challenged Mr Bush to send "the entire army" to Iraq.
The Iraqi insurgents would "bury 10 armies like yours", he said.
Earlier this month, Mr Bush announced the deployment of over 20,000 more troops in a bid to end the violence.
Site - a Washington-based organisation that analyses militant networks - posted the video and transcript on its website, but did not say how it obtained it.
In the tape - 14 minutes of footage with English subtitles - Zawahiri said that Mr Bush's strategy in Iraq was going to fail.
"I ask him, why send 20,000 (troops) only - why not send 50,000 or 100,000?" he said.
"Aren't you aware that the dogs of Iraq are pining for your troops' dead bodies?"
He said that al-Qaeda and the Taleban were regaining control in Afghanistan, and called on all Muslims to bear arms or support those bearing arms to defend Islam.
The message is the first apparent reaction by al-Qaeda to Mr Bush's planned "surge" in Iraq.
On 5 January, Zawahiri appeared in an audiotape posted on a website urging Somalia's Islamist militias to carry out attacks against Ethiopian troops.