Militants in the southern Iraqi city of Basra have kidnapped a British journalist and threatened to kill him if US forces do not leave the holy city of Najaf within 24 hours.

In a video, the journalist, barechested and with a bandage on his head, identified himself as James Brandon, 23, a reporter for The Sunday Telegraph.

"I'm a journalist, I just write about what is happening in Iraq ...(I'm) James Brandon from the Sunday Telegraph," the visibly shaken hostage said.

The "Telegraph, that's my paper," he said, turning to a masked captor.

Asked to give his address, the terrified man said: "London".

The militants said they had taken him hostage in protest against the US military assault on Najaf, one of the holiest cities for Shiite Muslims.

The US military and Iraqi forces began an offensive in the city yesterday designed to defeat a rebel militia they have been battling for more than a week.

"We are the sons of the Iraqi people," said the kidnapper in a black ski mask.

"We demand the withdrawal of the occupation forces from the holy city of Najaf in 24 hours, otherwise we will kill this British hostage," he said, patting Mr Brandon on the shoulder.

Mr Brandon was kidnapped yesterday when about 30 gunmen, some dressed as police, stormed into the Diafa Hotel in Basra, said Iraqi police captain Hashem Abdullah. Hotel owner Mohammed Uglah said gunmen found Mr Brandon and shot at him after he tried to escape, beating him over the head before taking him away. He had earlier said that the journalist was shot twice in the leg.

Hotel staff showed a check-in form filled in by the man, identifying himself as James Brandon, 23. According to the form, he had arrived in Basra on Wednesday.

The Sunday Telegraph confirmed Mr Brandon was working for the paper.

"James Brandon was in Basra filing material for this Sunday's newspaper among other projects," deputy editor Matthew d'Ancona said. "We are pursuing his situation with the greatest concern."

The Foreign Office confirmed that a British national had been abducted in Basra but said it could not confirm the person's identity as it was still trying to contact next-of-kin.

Kidnappers in Iraq have seized scores of hostages in recent months threatening to kill them in an effort to drive out coalition forces and companies supporting them.

There were reports today that Shiite cleric Muqtada al-Sadr's militant group had appealed for the kidnappers to release him.

The cleric's spokesman said today he had been wounded in the fighting in Najaf.

Al-Sadr is said to be hiding in the compound housing the Imam Ali shrine, surrounded by his followers.