A Nato aircraft has killed 20 people at an Italian ski resort by severing their cable car line.

All but one of the victims were foreign tourists - mainly German and possibly Polish and Hungarian - travelling in a cable car 6,000 foot up Mount Cermis in the Dolomites.

A Cavalese fireman said: "I saw the aircraft go to and fro at a very low level.

"They do it every day and we have protested on a number of occasions. Sooner or later something like this was going to happen."

Local police official Andrea Russo said: "All the four walls of the car had been opened up like a cardboard box.

"The bodies were all lying beneath the sheet metal. Most of them were torn apart."

An operator was treated for shock after his car - travelling in the opposite direction - was left dangling from the cable for four hours when the emergency brakes halted the system.

US defence secretary William Cohen said the pilot of the plane - attached to the Nato mission in Bosnia - was unaware he had struck the cable and injured anybody.

The plane sustained tail damage and the pilot made an emergency landing at its base, 60 miles away, in Aviano, northern Italy.

None of the three passengers on board the US Grumman Prowler aircraft were injured but a spokesman at the base said the pilot - on a routine training flight - had felt a bump.

Hardline Italian left-wing MPs have called for an end to low altitude Nato flights in Italy and a suspension of licenses for US bases there.

US President Bill Clinton has called Italian Prime Minister Romano Prodi to offer his condolences and pledge US assistance.

A cable car accident - caused by human error - killed 43 people in 1976, just 200 yards away from the scene of today's tragedy.