KARACHI, Feb 23 (IslamOnline & News Agencies) - Pakistani police were Saturday searching for a key suspect blamed in the abduction of U.S. journalist Daniel Pearl, whose killing has triggered horror and anger worldwide.

Speaking at his hotel in Beijing, U.S. President George W. Bush said the slaying would only strengthen U.S. determination in its war on terrorism.

"Those who would threaten Americans, those who would engage in criminal, barbaric acts, need to know that these crimes only hurt their cause and only deepen the resolve of the United States of America to rid the world of these agents of terror," Bush said.

President Bush expressed special sympathy for Pearl's wife Mariane's unborn baby, "who will now know his father only through the memory of others", reported Agence France-Presse (AFP). "All Americans are sad and angry to learn of the murder."

A Pakistani senior investigator said the police's most wanted man was Amjad Hussain Farooqi, who they believe drove Pearl from a hotel January 23 on his way to captivity and eventual death.

"So far there is no clue as to when and where the murder was carried out," the investigator said. "We are engaged in frantic efforts to find the body" and Farooqi, he said.

The U.S. and Pakistani governments have both vowed to track down those behind the slaying of the Wall Street Journal correspondent, reported Agence France-Presse (AFP).

Pakistan Interior Minister Moinuddin Haider said Friday police were looking for four more accomplices in the killing, using descriptions provided by a journalist who delivered a videotape showing Pearl being decapitated. Investigators also said police were hunting another suspect, an Arab who is thought to have helped Farooqi kidnap Pearl in this southern Pakistani city.

Officials declined to specify the name or nationality of the suspect, saying that would help the man escape. Police already have in custody British-born Sheikh Omar, the self-confessed mastermind of Pearl's abduction who told a court February 14 that Pearl was dead.

Omar is due to appear before a security-heavy Karachi court Monday when his 13-day remand runs out. A senior investigator said Omar "would now face a murder case".

Also detained are three militants accused of sending e-mails after Pearl was snatched showing the 38-year-old reporter with a gun to his head and listing demands, among them that the United States release Pakistanis detained from its military campaign in Afghanistan.

Top U.S. officials were adamant they would not bow to the demands, as authorities in Pakistan conducted a massive manhunt. The Pakistani news agency that received the video of Pearl's slaying said Friday that Pearl was killed after he read a statement saying that he was Jewish and that Muslims were being persecuted in several parts of the world.

"If the objective of these terrorists or those who perpetrated this murder was to move us away from our resolve, let me tell them that they are sadly mistaken," Pakistani president, Pervez Musharraf said on state television.

The general acknowledged last week on a visit to Washington that Pearl's kidnapping may have been part of a backlash against a crackdown on Islamic extremism he announced in a January 12 speech.

The United States on Friday hailed Pakistan's cooperation with the investigation and expressed hope that such help could bring the swift arrest of his abductors.

"Both the United States and Pakistan are committed to identifying the perpetrators of the crime and bringing them to justice," said State Department spokesman Richard Boucher.

"We'll continue to work closely with Pakistani authorities, who have provided excellent cooperation in this investigation all along."

On Saturday, Pakistani newspapers called for Musharraf to crush Islamic extremism. The Pakistani newspaper The News said: "Daniel Pearl's death should provide Pakistani authorities the ultimate justification to go after terrorism in all its shapes and forms, in all spheres of our society."

"After this any laxity in dealing with the issue will mean inexcusable complicity in crime," it wrote in an editorial. The News said Pakistan's failure to rescue Pearl was responsible "for the massive humiliation Pakistan is going to face in the world now." while the Dawn said the country's agencies "must now be held responsible for the failure to save Pearl's life."

"Pearl was innocent, doing his professional work and those responsible must be punished," Jamaat-i-Islami's deputy chief Ghafoor Ahmed told AFP. Party spokesman Riaz Durranim said the killing was "against the very teachings of Islam."

France's President Jacques Chirac, who branded the killing a "savage and cruel act of terrorism," also demanded the killers be brought to justice.