Police yesterday released film footage of two suspected arsonists behind an £18m trail of destruction.

Grainy footage from a CCTV camera has provided a major breakthrough in the hunt for those responsible for torching truck depots across Tyneside.

Police, who thought they were hunting for a lone arsonists, were amazed to discover pictures of two suspects fleeing the scene of the last inferno at Benfield Motors in Scotswood Road, Newcastle, on May 20.

And two sets of footprints were found alongside damaged fencing after a £1.5m blaze at Newcastle City Council's City works depot in Benwell, on March 4.

Now a five-figure reward has been offered to catch the men, likened to a terrorist cell, while an appeal will go out nationwide on tonight's (wed) Crimewatch programme.

Det Insp Steve Fear, leading the 40 detectives assigned to Northumbria Police's biggest arson manhunt, said: "We now have evidence that at least two suspects are behind these attacks.

"We have kept an open mind since this investigation began, but a new psychological profile is being drawn up.

"These are sophisticated, pre-meditated attacks but they are putting their own and other people's lives in danger.

"We still believe there is some involvement with the haulage trade because of the unique knowledge they seem to have of these yards.

"I believe somebody close to them knows what they are doing, but has not come forward yet to tell the police.

"They have to ask whether they want it on their conscience when these people kill someone."

The arsonists strike at night, cutting through fencing, smashing cabs with steel ball bearings, pouring accelerant inside the vehicles and setting them alight before fleeing.

The new evidence, gathered in their latest three attacks this year, was released today in a bid to solve the year-long investigation.

In each attack home-made fuses were used - taping handfuls of household matches together to set the fire raging.

Mick Nielsen, divisional fire brigade officer for Newcastle's West End, said: "This is the largest scale case of serial arson I have ever seen in 25 years in the fire brigade.

"Each incident has the same trademark signs. We are sure whoever does this visits the sites beforehand and plans the attack with military precision."

Keith Pugh, managing director of Owen Pugh, said: "We thought this was the work of a deranged loner - now this blows every theory out of the water.

"It looks very much like they have a mission to strike against the heavy goods industry in the North East.

"It makes you wonder if this is some sort of group of environmental extremists bent on ridding the region of lorries, although no group has ever claimed responsibility."

* Crimewatch is screened on BBC1 at 9.05pm tonight.