Sabotage by an insider at a major utility facility, including a chemical or oil refinery, could provide al Qaeda with its best opportunity for the kind of massive Sept. 11 anniversary attack Osama bin Laden was planning, according to U.S. officials.

A new intelligence report from the Department of Homeland Security issued Tuesday, titled Insider Threat to Utilities, warns “violent extremists have, in fact, obtained insider positions,” and that “outsiders have attempted to solicit utility-sector employees” for damaging physical and cyber attacks.

“Based on the reliable reporting of previous incidents, we have high confidence in our judgment that insiders and their actions pose a significant threat to the infrastructure and information systems of U.S. facilities,” the bulletin reads in part. “Past events and reporting also provide high confidence in our judgment that insider information on sites, infrastructure, networks, and personnel is valuable to our adversaries and may increase the impact of any attack on the utilities infrastructure.”

In the materials recovered after the Navy SEAL operation that killed Osama bin Laden in May, officials found evidence bin Laden sought to repeat the carnage of the Sept. 11, 2001, terror attacks on or around its ten year anniversary.

The Department of Homeland Security said in a statement there was no specific threat.

“DHS routinely shares information with its state and local partners on a wide-range of potential threats, and as part of this responsibility, DHS issued an intelligence note to its federal, state, local, tribal and private sector partners on July 19 regarding potential threats to private sector utilities. While DHS has no specific, credible intelligence of an imminent threat posed to the private sector utilities, several recent incidents highlight the on-going threat to infrastructure in the utility sectors from insiders and outsiders seeking facility-specific information that might be exploited in an attack,” DHS press secretary Matt Chandler said. “We will continue to work closely with our state and local partners, including our partners in the utility sector, to take steps to best protect from potential threats – including protecting our nation’s infrastructure. This includes sharing information as well as best practices.”

READ MORE: ABC NEWS