Three men have been indicted in connection to an alleged plot to attack financial institutions in New York, northern New Jersey and Washington, D.C., the Justice Department said Tuesday.

The suspects — Dhiren Barot (search), Nadeem Tarmohamed (search) and Qaisar Shaffi (search) — were arrested last year in England and are still being held there.

"Today's indictment sends a message about our resolve to terrorists: We will continue to use all tools at our disposal to protect our nation from the acts of terrorists and to prosecute those who plot to harm us, whether those individuals are found in the United States or overseas," Deputy Attorney General James Comey told reporters during an afternoon press conference at the Justice Department Tuesday announcing the four-count indictments.

Comey said Washington would seek extradition of the suspects after British authorities wrapped up a case charging them of plotting attacks in the United Kingdom.

White House spokesman Scott McClellan, speaking to reporters aboard Air Force One as President Bush returned to Washington from his ranch in Texas, called the indictments "another significant step in the global war on terrorism."

"We're going to continue to go after and pursue those who seek to do us harm and those who seek to do harm to the civilized world," McClellan said.

The three men are charged with conspiring to use weapons of mass destruction, providing material support and resources to terrorists, and conspiring to damage and destroy buildings.

The indictment alleges that the defendants entered the United States in 2000 and 2001 to conduct surveillance of several buildings in New York, Northern New Jersey and Washington, D.C. as part of a conspiracy to damage and destroy the buildings.

After discovery of the surveillance activities, the color-coded homeland security advisory level in the United States was raised from "elevated" (yellow) to "high" (orange) for those communities until November 2004. The indictment says the conspiracies to attack buildings were ongoing until August 2004, when the defendants were arrested in the United Kingdom.

If convicted of the charges in the United States, the defendants face a maximum sentence of life in prison on the charge of conspiracy to use weapons of mass destruction, 15 years in prison on each material support count, and 20 years in prison on the charge of conspiring to damage and destroy buildings.

"The conspiracy laid out in the indictment was designed to kill as many Americans as possible, and the alleged surveillance of these buildings makes these allegations all the more serious," Comey said.

Added David Kelley, the U.S. attorney for of the Southern District of New York: "The fact that these terrorists stalked their targets while surrounded by innocent and unsuspecting Americans going about their everyday affairs reminds all of us that a successful campaign against terrorism calls upon all of us to be ever-vigilant ... The entire law enforcement community is committed to this battle and will travel the globe to bring to justice any and all terrorists, particularly those plotting to commit terrorist acts on our soil."

Earlier in the day, New York City Police Commissioner Raymond Kelly described Barot as a "major Al Qaeda operative" and said the three had conducted surveillance of financial buildings in the city prior to the Sept. 11 attacks.

"We believe they were here in 2000 and perhaps early 2001 ... they may have been here in March 2001," Kelly said at a Tuesday press conference.

Kelly also explained the gap between the defendants' arrest and the indictment.

"The federal authorities were working with British authorities to accumulate this information," he said. "A lot of it was on hard drives that had to be downloaded, a lot was encrypted. There may still be more."

Kelly said that while the indictments were a gain in the War on Terror, the "overall threat" to the city had not diminished.

Not present at the press conference was New York City Mayor Michael Bloomberg, who was in Washington Tuesday to meet with new homeland security chief, Michael Chertoff (search), and to speak with lawmakers about getting more security funding for the city.

The eight-page indictment, from a grand jury in the Southern District of New York, does not mention Al Qaeda or Usama bin Laden (search). It was not clear why the defendants weren't also facing charges of being members of the terror network.

Read the charges by clicking here (pdf).

Barot, 32, is a Briton of Indian descent who converted from Hinduism to Islam some years ago. U.S. officials say he is a senior Al Qaeda (search) figure known within the organization by the aliases Abu Eisa al-Hindi, Abu Musa al-Hindi and Issa al-Britani. Officials believe he was in the United States under orders from bin Laden.

Tarmohamed, 26, was charged at the time of the arrests, along with Barot, with possessing plans of the Prudential building (search) in Newark, N.J.

Shaffi, 25, also was charged at the time with possessing an extract from the "Terrorist's Handbook" on the preparation of chemicals, explosive recipes and other information.

Barot, Shaffi and Tarmohamed are accused of plotting to use weapons such as improvised explosive devises and bombs on U.S. soil between 1998 and 2004. The grand jury also charges them with using video surveillance on financial buildings and surrounding neighborhoods as part of a terrorist plot in April 2001.

According to the indictment, Barot served as lead instructor at a jihad training camp in Afghanistan. He is also accused of applying to a college in New York in 2000 in order to conceal the true purpose of his trips to the United States. He never actually enrolled or attended any classes.

The indictment describes two trips the defendants allegedly took into the United States from London in 2000 and 2001. At one point during one of these trips — April 3, 2001 — Shaffi allegedly became ill and had to be treated at a New York hospital.

British authorities arrested the three last year as part of a separate terrorism investigation, but found evidence the men had monitored the New York Stock Exchange (search) and the Citigroup Center (search) in Manhattan, as well as the Prudential building in Newark.

In late July of last year, the Department of Homeland Security raised the color-coded terror alert to orange for U.S. financial centers after finding evidence terrorists were examining the New York-area buildings as well as the International Monetary Fund (search) and World Bank (search) buildings in Washington, D.C.

Officials later told FOX News that other potential targets included the American Stock Exchange (search), Nasdaq, Morgan Stanley, Lehman Bros., Goldman Sachs, the Federal Reserve Bank, Bear Stearns, AIG, MetLife and JP Morgan Chase.

Police and other security personnel set up concrete barriers and roadblocks outside the buildings after they were put on high alert. Employees were subject to searches and ID checks on their way to and from work.

Homeland security officials later acknowledged that intelligence pointing to the financial institutions plot was possibly up to four years old, but stressed that Al Qaeda has demonstrated patience in carrying out attacks.

Then-Homeland Security Secretary Tom Ridge (search) also said that some information discovered had been updated as recently as January of 2004.

The threat level was lowered to yellow in November for northern New Jersey and Washington. New York City has been on high alert since the Sept. 11, 2001 attacks.

FOX News' Anna Persky, Jane Roh and The Associated Press contributed to this report.