British police have launched an investigation into the disappearance of secret counter-terrorism plans for London's Heathrow Airport.

The Sun newspaper reports the documents were found by a motorist on a road near the airport. CRIENGLISH.com reported Monday.

They are said to list sites suitable for launching rockets at aircraft. The plans are also thought to contain confidential information about police measures in case of a calamity.

A Scotland Yard spokeswoman said she could not discuss the contents of the documents nor where they were found.

Source: CRIENGLISH.com