The U.S. government is working to free a Wall Street Journal reporter taken hostage while on assignment in Pakistan, the White House said Monday.

U.S. officials have been in contact with authorities in Pakistan about the disappearance of Daniel Pearl, 38, and will "give whatever help can be given" to obtain his release, White House spokesman Ari Fleischer said.

"He was a journalist just trying to do his job. This is a serious matter, and it is being pursued by the United States government," Fleischer said.

State Department spokesman Richard Boucher said Secretary of State Colin Powell discussed the case in a telephone conversation with Pakistani President Pervez Musharraf on Monday and "noted our strong interest in seeing it resolved."

Pearl has been missing since Jan. 23, when he left to meet with members of a radical Islamic group in Karachi, Pakistan, that was believed to have ties to the Al Qaeda terrorist organization, the Journal reported Monday.

An e-mail accusing Pearl of being a CIA officer posing as a journalist was sent Sunday to various U.S. newspapers from a group calling itself The National Movement for the Restoration of Pakistani Sovereignty, which claimed responsibility for Pearl's disappearance.

In Pakistan, police sources speaking on condition of anonymity told The Associated Press they had not heard of the group. Instead, they believe Pearl was kidnapped by Harkat ul-Mujahedeen, which has close ties to Al Qaeda and is on the U.S. government's terrorist organizations list.

The Journal and the CIA have dismissed the allegation that Pearl is with the CIA.

"Although we don't normally discuss such matters, Daniel Pearl does not now nor has he ever worked for the CIA," said agency spokeswoman Anya Guilsher.

The e-mail was accompanied by four photographs purporting to show Pearl chained in captivity. One showed him hunched over with a gun to his head.

In the e-mail, the group demanded that Pakistanis detained in Cuba by the U.S. military be allowed access to their lawyers and families and that Afghanistan's former ambassador to Pakistan and the Taliban's most-recognized spokesman, Abdul Salam Zaeef, be handed over to Pakistan.

The group also sent an attachment demanding that F-16 fighter jets purchased by Pakistan in the 1980s be released. The planes were never delivered because of U.S. sanctions related to Islamabad's nuclear-weapons program.

"In the interest of humanity, the terrorists should release Mr. Pearl immediately," said Steven Goldstein, a vice president of Dow Jones & Co., the Journal's owner. He said the newspaper, which received the e-mail from a reporter at another newspaper, has not had any direct contact with the group.

"As a private citizen employed by an independent newspaper, neither Mr. Pearl, nor we, can change the policies of the United States or Pakistan," Goldstein said.

The e-mail was sent using Microsoft's free e-mail service, Hotmail, with the user name "kidnapperguy," The New York Times reported Monday.

The Journal quoted the e-mail as saying Pearl was being held "in very inhuman circumstances quite similar in fact to the way Pakistanis" are being kept in Cuba.

Pearl has been a Journal staff reporter for 12 years, in Atlanta, Washington and London, and has been South Asia bureau chief since 2000. He was accompanied by his wife, Mariane, who is expecting the couple's first child in May.