Daniel Pearl does not now, nor has he ever, worked for the CIA

CIA spokeswoman Anya Guilsher

A group calling itself the National Movement for the Restoration of Pakistani Sovereignty released a photograph of the journalist, Daniel Pearl, with a gun being held menacingly to his head.

An accompanying message sent to US news organisations said Mr Pearl was being held in inhuman conditions - similar, it said, to those experienced by al-Qaeda suspects being held at the US base at Guantanamo Bay.

The journalist has been missing nearly a week

Their captive would receive better treatment only if conditions at Camp X-Ray improved and Pakistani detainees were sent home, the group said in an e-mail.

Mr Pearl, 38, the Wall Street Journal's South Asia Bureau chief, went missing last Wednesday when he was in Karachi to interview leaders of radical Islamic groups

Both the newspaper and the US authorities have denied his captors' claims that he works for the CIA.

Investigation

Pakistan police sources told The Associated Press they believed Mr Pearl was kidnapped by Harkat ul-Mujahedeen, which is closely linked to Osama Bin Laden's al-Qaeda network.

If the Americans keep our countrymen in better conditions, than we will better the conditions of Mr Pearl

Emailed warning

Harkat is on the US Government's list of terrorist organisations, and a number of its fighters were known to have been killed in the US-led Afghan campaign.

Police have questioned and released five men in connection with Mr Pearl's disappearance, but say they are no nearer to tracing his whereabouts.

The Wall Street Journal said the photos it had received of Mr Pearl appeared legitimate, but it had had no direct contact with the alleged kidnappers.

The hostage has been WSJ South Asia bureau chief since 2000

"In the interest of humanity, the terrorists should release Mr. Pearl immediately," Steven Goldstein, a vice president of Dow Jones & Co, the Journal's owner, said.

The e-mail was sent sent using Microsoft's free e-mail service, Hotmail, with the user name "kidnapperguy," according to the New York Times - which was among the US media recipients.

WSJ quoted it as saying that Mr Pearl was being held "in very inhuman circumstances - quite similar in fact to the way Pakistanis and nationals of other sovereign countries are being kept in Cuba by the American army".

The e-mail reportedly went on to say: "If the Americans keep our countrymen in better conditions, than we will better the conditions of Mr Pearl and all other Americans that we capture."

It also called for the release of Afghanistan's former ambassador to Pakistan, Abdul Salam Zaeef, who is one of the highest-ranking Taleban officials in US custody.