WASHINGTON: An Al Qaeda cell in Syria, that was targeted in American military airstrikes last month, could still be working on a plan to attack the United States or its allies and is “looking to do it very, very soon,” the head of the FBI says.

“Given our visibility we know they're serious people, bent on destruction,” FBI Director James Comey said.

The Khorasan Group, a small but battle-hardened band of Al Qaeda veterans from Afghanistan and Pakistan, was the target of US strikes near Aleppo, Syria.

In an interview broadcast Sunday on CBS' “60 Minutes,” Comey said the militants were “working and, you know, may still be working on an effort to attack the United States or our allies, and looking to do it very, very soon. “

Senior US officials have not said whether the group's plots have been disrupted.

Comey said the US believes there are about a dozen Americans fighting alongside extremist groups in Syria.

He said if someone has fought alongside the Islamic State militant group and tries to come back to the US, “we will track them very carefully."

He said Americans should have confidence in changes made since the Sept 11, 2001, terrorist attacks, pointing to a government “better organised, better systems, better equipment, smarter deployment. We're better in every way that you'd want us to be since 9/11.“

Comey also addressed cybercrime, comparing Chinese computer hackers to a “drunk burglar” who steals with reckless abandon, costing the US economy billions of dollars every year.

He said the hackers target the intellectual property of US companies in China every day.

“They're kickin' in the front door, knocking over the vase, while they're walking out with your television set. They're just prolific. Their strategy seems to be: 'We'll just be everywhere all the time. And there's no way they can stop us,“ Comey said.

The Justice Department earlier this year announced a 31-count indictment against Chinese hackers accused of breaking into computer networks at steel companies and the manufacturers of solar and nuclear technology, with the goal of gaining a competitive advantage.

China has denied the allegations.