PORTLAND – Despite Portland’s involvement in the attack on the World Trade Center, a top FBI official says he is convinced there is no substantial terrorist presence in Maine.

“Maine is not a dangerous place in terms of terrorists,” said Charles Prouty, special agent in charge of the FBI’s Boston Field Office. “There are not a lot of terrorists up there.”

But federal investigators concede that they still don’t know why Mohamed Atta, the mastermind of the Sept. 11 attack, and Abdulaziz Alomari embarked on their mission from Portland International Jetport.

Reported sightings of Atta in the Portland area in the weeks and months before the hijacking fueled speculation about possible terrorist links to the city.

Suspicions grew when authorities learned a plane had been left at the jetport by a Saudi businessman sought for questioning and when authorities revealed that a money transfer business linked to terrorism had an account at a local bank.

The Boston Field Office, which covers Maine, New Hampshire, Massachusetts and Rhode Island, investigated more than 8,700 leads, none of which pointed to a network of terrorists in Maine.

Some of those leads followed an FBI presentation in Portland detailing the movements of Atta and Alomari during the hours before the attack.

The goal of Prouty’s presentation was to elicit additional information from the public about the men’s activities. No similar presentations were held in other cities where the terrorists operated, leading some people to believe that terrorist cells must operate in Portland.

Not so, according to Prouty. “The primary reason was we were interested in knowing why they went up to your community. We don’t really know why,” Prouty said.

He also said the FBI has no indication that Atta and Alomari spent any time in Portland before their arrival on the eve of the attack.