The shadowy group "announced it had abducted General Salah Hassan Zaidan al-Lami, an in-law of Iraqi Defense Minister Hazem al-Shaalan, who is in charge of military personnel affairs at the defense ministry, and one of his relatives," it said.

"The captors demanded in a video received by Al-Jazeera a halt to military operations in Najaf and the release of Sheikh Ali Smeisim, who was arrested by Iraqi authorities" earlier Wednesday.

The video showed the two presumed hostages, with two gunmen partly seen in the background.

There was no specific threat in the TV broadcast against the two supposed captives.

Iraqi police said Smeisim was arrested in the besieged holy city of Najaf, where Sadr's Mehdi Army militia is pinned down by US and Iraqi government forces around the sacred Imam Ali mausoleum.

Shaalan warned on Tuesday that Sadr would be killed or captured if he resisted Iraqi troops.

"If Moqtada Sadr surrenders, he will be safe and sound. If he resists, the only thing for him is death or prison," Shaalan told reporters at a US base outside Najaf.

WAR.WIRE