Weapons testing at Rinella

The Rinella water tanks have seen it all - only last week, they provided the setting for the 1453 Siege of Constantinople, as well as the testing ground for a mysterious weapon, an "incendiary firing catapult", which was used at the time.

Bright flames were sent shooting across the surface of the tank as a team of experts tried to solve the mystery of the weapon and reproduce it, using only ancient materials and techniques.

A highly explosive oil, which was used to recreate the weapon, had to be shipped from Azerbaijan, said young producer Ana Lloyd of Windfall Films, a UK production company.

The pyrotechnic display, watched over by a fire crew from Malta International Airport, was created for an episode of a documentary, Inventing the Past, which is to be aired on Discovery Channel in April and focuses on "unresolved, technological mysteries of the past".

It should also be aired on the Canadian History Channel, France V and Channel 4, said Ms Lloyd.

The Byzantine Fireship, the working title of the one-hour episode of the four-part series, gathered a team of related experts - from a Birmingham University Byzantine historian to metalworking and ancient weapons specialists, an engineer and an explosives expert - who together at the tanks cracked the mystery behind what was known as Greek, or prepared fire, an ancient form of napalm, reference to which is made in ancient texts.

In Malta, around four days were spent testing the weapon, which proved to be successful, said Producer's Creative Partnership production coordinator Joseph Formosa Randon.

Together with director Mark Lewis, Ms Lloyd and the production team researched, experimented, discovered, learnt and filmed.

The Byzantine Fireship centres around the four-month siege, which marked the end of the Byzantine Empire by a Turkish assault. The historical background and small-scale drama reconstructions were filmed in Istanbul, where the entire documentary was intended to be shot.

"We had originally thought of doing the whole thing in Turkey before we learnt about the tanks. We came to Malta on the way to a recce in Istanbul and we knew immediately that it was the place: the people were fantastic, as well as divers and other experts, and the studios had the right boats."

Malta was considered to be a "controlled and fabulous location" - certainly better than the Bosphorus as was planned originally, said Ms Lloyd.

The Bosphorus' busy shipping lanes were not the most ideal environment for the testing of a flame-throwing catapult and the "controlled space" of the tanks was a major bonus.