Roobik Mirzabegi, 51, used four garages in Leeds to defraud the taxpayer by issuing thousands of invalid MOT certificates for vehicles that were not properly tested.

Leeds Crown Court heard the scam continued for more than a decade, making it impossible to estimate how many faulty cars were allowed to remain on Yorkshire's roads.

Mirzabegi, of Old Lane, Beeston, Leeds, was convicted after two crown court trials and a major joint operation involving police and the Vehicle and Operator Services Agency.

He was found guilty of three counts of conspiracy to defraud and concealing or transferring proceeds of criminal conduct.

But a jury cleared him of doing an act tending or intending to pervert the course of public justice and a further charge of conspiracy to defraud.

Mirzabegi was tried along with his brother Hakop Mirzabaigian, 53, of The Avenue, Harewood, and his estranged wife Julie Mirzabegi, 51, of Broadcroft Chase, Wakefield.

Mirzabaigian, who earns £650 a day working as a consultant in the Middle East, was ordered to pay a £6,500 fine for his part in the conspiracy.

He was convicted of one count of conspiracy to defraud, but cleared of forgery and another charge of conspiracy to defraud.

Julie Mirzabegi, who was found guilty of assisting another to retain the benefit of criminal conduct and obtaining services by deception, will be sentenced along with Roobik Mirzabegi at Leeds Crown Court on a date to be fixed.

Ten men from West Yorkshire were sentenced in January after pleading guilty to a string of offences relating to the scam.

Barry Davis Jr, 35, of Main Street, Methley, admitted money laundering by assisting another to retain the benefit of criminal conduct and three counts of conspiracy to defraud. He was given a 10-month prison sentence, suspended for two years, and ordered to do 300 hours' unpaid work.

His father Barry Davis Sr, 63, of Main Street, Methley, was given an 18-month conditional discharge after admitting conspiracy to defraud and money laundering by assisting another to retain the benefit of criminal conduct.

Goorgen Haghverdi, 52, of Gledhow Towers, Gledhow, Leeds, pleaded guilty to forgery and was given a two-year community order.

The other seven offenders were given punishments ranging from suspended prison sentences to an absolute discharge after admitting conspiracy to defraud.

They were Gary Barker, 51, of Bradford Road, Otley; Jonathan Beales, 47, of Disraeli Terrace, Beeston, Leeds; Michael Waite, 37, of Temple Avenue, Rothwell; Paul Tunstall, 45, of Aberfield Crest, Belle Isle, Leeds; Michael Szymansky, 55, of Miles Hill Road, Potternewton, Leeds; Graham Barugh, 56, of Chapel Street, Leeds; and Michael Jackson, 26, of Throstle Lane, Middleton, Leeds.