Rick Bates: "Learn from lessons"

Before 11 September, passengers boarding flights from small airports in Scotland were not always searched. New regulations have made security checks statutory.

"We are not here to teach the US lessons, in this instance we are here to learn from them to see how they reacted to the problems of September 11."

The conference also heard from Detective Sergeant Joseph Leather, from the Port Authority of New York and New Jersey, which owned the World Trade Center.

He was one of the leading officers at the scene of the disaster.

Debris 'unbelievable'

DS Leather said: "Your criminals are our criminals. Our terrorists are your terrorists. Your enemies are our enemies."

He played operational video footage to the conference, showing the scenes of chaos and carnage which he witnessed after the planes hit the twin towers.

"The debris and the cloud was just unbelievable," he said.

The World Trade Center was destroyed

"We stood there wanting to do something but when the building starts to fall, you are running for your life.

"But you don't want to be doing that because your colleagues are in the building but you are running for your life because the cloud is chasing you.

"I always wondered what volcanic ash was like and I got a taste of something similar which I would not like to experience again."

Two of the authority's officers were rescued after surviving for 18 hours under rubble.

Mr Leather, who has worked at the port authority for 22 years, and his team are responsible for policing three major airports, including JFK and Newark.