The presence of Sept. 11 hijackers and other Al Qaeda operatives in San Diego has led investigators to believe the operatives were sent to scout the Navy's largest West Coast port, according to a federal law enforcement source.

Investigators believe Sept. 11 hijackers Nawaf Alhazmi and Khalid Almihdhar, who arrived in California in January 2000, most likely were assigned to identify San Diego-based Navy ships to attack, said the federal official, who spoke to The Associated Press on condition of anonymity.

In October 2000, Al Qaeda attacked the Navy warship USS Cole in Yemen.

Alhazmi and Almihdhar were aboard American Airlines Flight 77 when it crashed into the Pentagon, but fears about Al Qaeda agents in the area remain.

In a recent interview, Gov. Gray Davis said "the FBI has shared with us the probability of at least a couple cells active in California."

San Diego is home to two nuclear-powered aircraft carriers and five nuclear-powered submarines, as well as the headquarters of the SEALs, the Navy's special operations force. A signature feature of the region is the two-mile bridge that links San Diego to Coronado.

The city served as a base for a "high number of hijackers and associates who lived, worked and studied" in the area, James Nagel, a special agent with the State Department's Bureau of Diplomatic Security, has said in court documents.

In May, the FBI began checking with dive shops in the city and around the country to see if Al Qaeda operatives had been taking scuba training. Special operations Navy divers and San Diego Harbor police started training in July to spot potential terrorist threats in the port, and the U.S. Coast Guard has asked recreational boaters to look for and report any suspicious activity.

John Iannarelli, an FBI spokesman in San Diego, said his agency is investigating the extent of the hijackers' support network in or near the city. He would provide no further details.

Last month, authorities in Spain seized videos of the Golden Gate Bridge, Disneyland and Universal Studios from suspected Al Qaeda terrorists.

An Al Qaeda training manual recovered by police in England lays out the organization's missions. Topping the list is gathering information about "the enemy, the land, the installations." No. 6 is "blasting and destroying the places of amusement, immorality and sin," and No. 8 is "blasting and destroying bridges leading into and out of the cities."

Just days before their Jan. 15, 2000, arrival in the United States, Alhazmi and Almihdhar traveled to Malaysia to meet with an Al Qaeda lieutenant named Tawfiq Attash Khallad, labeled the mastermind of the USS Cole attack. Those who attended the meeting scouted potential targets, the law enforcement source said.

Investigators in San Diego have divulged little of what they've learned about Almihdhar and Alhazmi. The pair attended a local mosque, worked at a gas station and took a few flight lessons. Almihdhar flew home to Saudi Arabia, but returned in the summer. By the end of 2000, they were gone.

After the Sept. 11 attacks, authorities questioned anyone who met with them and rounded up a handful of Middle Eastern men as material witnesses, three of whom were charged with crimes unrelated to terrorism.