The Justice Department is investigating whether a naturalized U.S. citizen from the Philippines stole classified documents while he worked in the office of Vice President Cheney and provided the information to opposition politicians in Manila, Bush administration officials said yesterday.

The possibility that Leandro Aragoncillo was passing the material while stationed as a U.S. Marine security official at the White House marks a dramatic expansion of the case against him and a former Philippine police official, Michael Ray Aquino. Both were arrested and charged in federal court in Newark last month with sending classified information obtained this year to the Philippines -- more than two years after Aragoncillo left the White House and went to work as an FBI intelligence analyst.

Officials from the White House, Justice Department and FBI declined to comment late yesterday, other than to confirm that Aragoncillo first went to work at the White House in 1999, when Al Gore was vice president. ABC News reported last night that Aragoncillo had admitted taking classified documents while he worked in Cheney's office. Officials with the FBI and the U.S. attorney's office in Newark declined to comment on the report.

Joseph Estrada, the former Philippine president who was forced from office four years ago by mass demonstrations, has acknowledged receiving documents from Aragoncillo while the suspect was still in the Marines. Estrada told a Philippine newspaper last month that Aragoncillo had passed material while visiting him at the Veterans Memorial Medical Center in Manila, where the former president was receiving treatment while being held on corruption charges from 2001 through 2003. Part of that stay would coincide with Aragoncillo's time in Cheney's office.

Estrada, who remains under house arrest, said in a statement published in the Philippine Daily Inquirer that the information was "non-classified" and that he was unaware of any illegal activity by Aragoncillo.

"Why would they include me in that mess? I know nothing about issues involving him," Estrada told the newspaper.

The prosecutions of Aragoncillo and Aquino have ignited a political firestorm in the Philippines, and officials from the two countries say the United States is now caught in a feud between President Gloria Macapagal Arroyo and rivals attempting to force her from office.

Federal prosecutors in New Jersey charged last month that Aragoncillo conspired with Aquino to steal more than 100 documents this year from the FBI, CIA and State Department. The men are accused of feeding classified material about the Philippines to politicians seeking to topple the government.

Aragoncillo retired in 2004 after 21 years in the Marines and began working for the FBI as an intelligence analyst. Reports apparently based on the classified material allegedly downloaded by Aragoncillo are being published in the Philippines. The reports reveal not only sources of sensitive U.S. information but include frank and unflattering assessments of Philippine leaders.

In one such report published in a Manila newspaper, comments attributed to diplomats at the U.S. Embassy described Arroyo as weak and overbearing with little popular credibility. Her vice president was called inept and unfit to take her place. Clandestine discussions among dissident soldiers are detailed, and the president's chances of surviving a coup are weighed.

Aragoncillo, 46, and Aquino, 39, were arrested in New Jersey on Sept. 10 and are being held without bail. Aquino, a former deputy director of the Philippine National Police and a Philippine national, is slated to be formally indicted in Newark today, according to one law enforcement official.

A criminal complaint filed in U.S. District Court in New Jersey charges that Aragoncillo shared the classified documents with Aquino as well as with two high-level Philippine public officials and a third former high-level official. Speculation is raging in Manila about their identities, but U.S. prosecutors have yet to reveal the names.

"We're talking about opposition people and their desire to replace the current administration," said a U.S.-based American official familiar with the investigation, speaking on condition of anonymity because the case is active. "They're not inside the current administration." The official said that those who received the information would be identified after the case goes to trial.

But several prominent critics of Arroyo's government have acknowledged that they obtained information from Aragoncillo and Aquino.

Sen. Panfilo "Ping" Lacson, who unsuccessfully challenged Arroyo in the presidential election last year, said in an interview that he had received e-mails from Aquino. Lacson, a retired national police chief, was the head of a special organized crime task force, and Aquino was a senior aide on that force.

Lacson said some of the e-mails Aquino sent were widely distributed to current and former members of the Philippine national police force while others were personal communications. He added that he did not consider the information to be sensitive intelligence, calling it nothing unusual.

"This was classified because it would embarrass the United States. There are opinions provided by certain officials of the United States government," he explained.

Although he said he had no direct knowledge of the U.S. investigation, Lacson said he expected he would be named in the United States as one of the three Philippine officials to be sent material by Aragoncillo and Aquino.

According to the criminal complaint, federal investigators first took an interest in Aragoncillo after he tried to intervene in behalf of Aquino, who had been arrested in March for overstaying a tourist visa.

Aquino had come to the United States almost four years earlier and settled in New York. When he left his homeland, he was under indictment for alleged involvement in the kidnapping and murder of a public relations executive who had quarreled with Estrada, and the man's driver.

After Aragoncillo contacted U.S. immigration officials this spring, identifying himself as an FBI employee and Aquino's friend, the FBI launched an audit of its internal database, which offers access to documents from various government agencies.

Investigators discovered Aragoncillo had used his top-secret clearance to download and print information relating to the Philippines although the material was outside his area of assignment, the complaint alleges. He then allegedly forwarded the information by e-mail, telephone and text message to the officials in the Philippines.

Federal prosecutors have charged the men with conspiracy and acting as unregistered agents under the direction of foreign officials. Aquino's attorney has denied the allegations. Aragoncillo has offered no public statement.

A U.S. official familiar with the investigation said Aragoncillo was paid to steal the information he obtained, but e-mail messages cited in the complaint also portray him as having an interest in shaping the politics of his birthplace.

Politics in the Philippines have been convulsive since Arroyo was elected to her first full term last year. Her opponents accused her of rigging the vote and sought this summer to impeach her. Arroyo's allies in Congress squelched that bid last month.

Last month, the Philippine Daily Inquirer published a series of articles detailing what it said were classified U.S. Embassy reports about the political turmoil. The newspaper said that it had received the documents from a source who wanted to remain anonymous and that it believed them to be among those downloaded by Aragoncillo.

In one document, Joseph Mussomeli, deputy chief of the U.S. Embassy at the time, reportedly advised that Arroyo's public support had faded and elements of all Philippine military services were planning an operation to remove her. In another, citing military and civilian contacts, he wrote that Philippine generals and more radical junior officers were separately plotting to oust her.

A document from late July reportedly detailed coup discussions at a secret conclave of about two dozen young army and naval officers in Manila. Another account, citing a clandestine source, described Arroyo calling an emergency meeting of her commanding generals to ensure their backing.

Philippine Justice Secretary Raul Gonzalez said in an interview that he had asked the U.S. Embassy for information about the investigation, including specifics regarding the classified documents and who in the Philippines received them. He said he was still awaiting a response.

"These are things that will give us an idea about the extent of the participation of our people here and the reasons they are doing this, if it really forms part of their scenario to destabilize the government," Gonzalez said.

Sipress reported from Manila.

Leandro Aragoncillo was a U.S. Marine security official at the White House. He later became an FBI intelligence analyst.