Washington ? Three men with suspected al-Qaida ties, already in British custody, were charged Tuesday with a years-long plot to attack the New York Stock Exchange and other East Coast financial institutions.

Discovery of the alleged terrorist plan last summer prompted the Homeland Security Department to raise the terror alert for the targeted buildings, located in New York, Washington and Newark, N.J. Security in those cities also was tightened.

A four-count indictment returned by a New York City grand jury alleges the men, all British citizens, visited and conducted surveillance of the buildings and surrounding neighborhoods between August 2000 and April 2001.

The plot was foiled when Pakistani investigators seized a computer with information from the surveillance. British authorities were alerted and arrested eight men, including the three suspects, on terrorism-related charges last August, Deputy Attorney General James B. Comey said.

The indictment “sends a message about our resolve to terrorists,” Comey said at a Justice Department news conference.

The grand jury returned the indictment on March 23 but it was unsealed only Tuesday. Named in it are Dhiran Barot, 33, Nadeem Tarmohammed, 26, and Qaisar Shaffi, 26. They could receive life sentences if convicted of the most serious charge, conspiracy to use weapons of mass destruction in the United States. The indictment lists those weapons as improvised explosive devices and bombs.

U.S. officials claim Barot is a senior al-Qaida figure, known variously as Abu Eisa al-Hindi, Abu Musa al-Hindi and Issa al-Britani.

Although they allegedly were doing their surveillance at the same time the 9-11 hijackers were making their final preparations, nothing in the indictment links this group to the hijackers.

The indictment does not allege any specific actions by the men in the United States or elsewhere after April 2001, though Comey said their plotting continued.