The disruption of a terror plot by British authorities last week is an example of international intelligence authorities working successfully together, Attorney General Alberto Gonzales said Wednesday.

Speaking to the World Affairs Council of Pittsburgh, Gonzales said it takes a network of international intelligence and law enforcement agencies to defeat terror networks, such as Al Qaeda.

Gonzales sidestepped the issue of whether the United States may be acting too soon to disrupt alleged terror plots. Some critics said British agents were able to round up more suspects by watching the terror plot unfold over time.

"Decisions about arrest are difficult ones that must be made on a case by case basis," Gonzales said.

Responding to written questions after the speech, Gonzales denied that the U.S. engaged in torture as part of its anti-terror policies. The Department of Justice strictly follows existing laws and does not violate the Constitution, he said.

Gonzales said prisoners are treated humanely in accordance with the spirit of the Geneva convention, which he called a "very important document."

But Gonzales insisted the U.S. prison at Guantanamo Bay, Cuba, is necessary even though it might be black eye for the U.S. image abroad.

"The perception is much worse than the reality," he said.

Some prisoners released from Guantanamo Bay already have begun fighting U.S. forces again, he said. He did not give any specific details.

In his speech, Gonzales acknowledged the importance of closely monitoring extremist Web sites, prisons and other venues that have been used to recruit radicals.

"Isolated souls" can be just as dangerous as Al Qaeda, he said.

Gonzales sidestepped the issue of whether the United States may be acting too soon to disrupt alleged terror plots. Some critics said British agents were able to round up more suspects by watching the terror plot unfold over time.