ASSOCIATED PRESS Wall Street Journal reporter Daniel Pearl is shown with a gun held to his head in this photo obtained yesterday. The Wall Street Journal is calling for the group that claimed to have seized Pearl, missing in Pakistan since Jan. 23, to release him.

ISLAMABAD, Pakistan - An e-mail purportedly sent yesterday by kidnappers holding Wall Street Journal reporter Daniel Pearl threatened to kill him within 24 hours. It also warned American journalists to leave the country within three days.

There was no way to authenticate the e-mail, which was sent to both Western and Pakistani news organizations.

The e-mail claimed that Pearl, the Journal's South Asian bureau chief who disappeared a week ago in Karachi, was an agent for the Israeli intelligence service, the Mossad.

"Therefore we will execute him within 24 hours unless Amreeka (America) fulfills our demands," said the e-mail. The message also criticized the United States for not providing lawyers and trials for Pakistanis detained on terrorism-related charges.

The e-mail accused U.S. journalists of working for intelligence agencies and warned "all Amreekan journalists" working in Pakistan to leave the country within three days.

"Anyone remaining after that will be targeted," it said.

The message was unsigned, but had similar phrases as e-mails sent over the weekend by the group claiming to hold Pearl, which called itself the National Movement for the Restoration of Pakistani Sovereignty.

The Dow Jones news agency published news that a threat had been made against Pearl.

In a statement yesterday, The Wall Street Journal denied that Pearl was an agent of any government. "He is a reporter for us - nothing more or less," the statement said. "He cannot affect the policy of the U.S. or Pakistani government. Nor can we."

The newspaper, which is owned by Dow Jones, also called for the reporter's release, saying: "Nothing will be served by continuing to hold him. Killing or harming Danny would only discredit the cause of the people holding him."

Earlier yesterday, police said they had arrested Sheik Mubarak Ali Shah Gilani, an Islamic leader with whom Pearl was trying to arrange an interview when he disappeared.

Gilani, head of the small militant group Tanzimul Fuqra, was apprehended in the northern city of Rawalpindi and transported to Karachi, police official Mazoor Mughal said.

There was still no word on where Pearl was being held by his captors, but police said raids were carried out yesterday in several Pakistani cities in connection with the investigation.

When trying to meet Gilani, Pearl was working on various stories, including possible links between Pakistani groups and Richard C. Reid, accused of trying to blow up an American Airlines plane with bombs hidden in his sneakers.

The group that said it had abducted Pearl was previously unknown. The weekend e-mails showed pictures of Pearl, 38, in chains with a pistol pointed at his head. It also included a list of demands, including better treatment for Pakistanis held with other terrorist suspects by U.S. authorities at Guantanamo Bay, Cuba.

Pakistani authorities said Pearl was most likely being held by a known radical Muslim faction linked to the al-Qaida terrorist organization.

The managing editor of The Wall Street Journal sent a six-paragraph e-mail back to Pearl's captors, appealing for them to release him and mentioning the reporter's family.

"You should know that Danny has a wife," the e-mail by Managing Editor Paul Steiger read. "She is a citizen of France, and also a journalist. She is also six months pregnant with their first child. I would like you to know that she is greatly distressed over Danny's situation."

"I encourage you to correspond with me further through this e-mail address," Steiger wrote in the message.

Meanwhile, a former journalist who was at the center of a similar kidnap drama in the 1980s said the U.S. government will never negotiate with Pearl's abductors.

"There is nothing that the American government can or will give them," said Terry Anderson, who spent nearly seven years as a hostage of Islamic extremists in Lebanon before his release in December 1991. "They have to understand that kidnapping journalists is not a useful tactic."

Anderson was Middle East chief of services for The Associated Press when he was taken hostage in Beirut in March, 1985, by the pro-Iran Hezbollah faction.

The U.S. government refused to negotiate for his release on grounds that it could encourage more abductions - a strategy that paid off through a decline in hostage-taking of journalists, according to Anderson.

"The night before they released me, my captors told me that it hadn't been a useful tactic," said Anderson, who later wrote a book on his experiences and taught journalism at Columbia University and Ohio University.

The New York-based Committee to Protect Journalists and the Paris-based Reporters Without Borders also called for Pearl's release.

"Targeting reporters who are working independently to report the news will never advance anyone's political agenda," said CPJ executive director Ann Cooper.

"It is totally absurd to make a journalist the scapegoat of his country's foreign policy," said RPB secretary-general Robert Menard.