A hard drive sold on the online auctioning website eBay reportedly contains highly sensitive details of a US missile air defense system.

The UK state telecommunications operator, BT, had discovered the information on one of the hard drives purchased by its Security Research Centre, The Daily Mail reported on Thursday.

The drive reportedly contained the test launch procedures for the Terminal High Altitude Area Defense, known as THAAD.

The ground to air missile defense system, which uses a hit-to-kill approach to shoot down short- and medium-range ballistic missiles, was last tested in March.

The US-made THAAD and the advanced Aegis combat system are scheduled to be deployed in Israel for Tel Aviv's largest military exercise in history.

Israel has announced that it is set to mobilize its army to hold the large scale exercise on June 2.

The hard disk, which came from an unspecified location, also contained security policies, blueprints and employee data from Lockheed Martin -- the company responsible for THAAD.

A spokesman for the company told the daily that "Lockheed Martin is not aware of any compromise of data related to the Terminal High Altitude Area Defence program."

"Until Lockheed Martin can evaluate the hard drive in question, it is not possible to comment further on its potential contents or source," he added.

THAAD intercepts ballistic missiles in the high stratosphere but has the capability to intercept targets both in and coming from the outer reaches of space.

The United Arab Emirates, which accounts for the largest weapons purchases in the Middle East, has decided to spend a reported $7 billion on the American missile defense system.

The reported information leak comes at a time when Tel Aviv has been heading steadily toward a confrontation with Tehran over its nuclear activities, citing fears that a "nuclear Iran" is the prime existential threat to its security.

Earlier in March, hawkish Israeli Prime Minister Benjamin Netanyahu raised the alarm and spoke of a major military conflict in the upcoming months.