Four men who conned banks into handing over £160 million for faked contracts to lay fibre optic cables in sewers have been jailed.

Stephen Dartnell, 60; George Alexander, 50; Simon Mundy, 50, and Carl Cumiskey, 56, were all convicted of the three-year scam after a five-month trial at Southwark Crown Court.

Dartnell and Alexander, working for Total Asset Finance (TAF), conspired with Cumiskey, of H2O Networks Limited, to create, sell and sign falsely inflated or entirely fabricated contracts from H2O to lenders Barclays Bank and KBC Bank.

And Mundy was paid nearly £900,000 in bribes to act as an "inside man" at KBC to authorise the loans to Warrington-based TAF.

Between 2007 and 2010 nearly £160 million in loans were secured but all money was repaid to Barclays and KBC's total losses amounted to £117 million, the court heard.

Mundy used the money to pay his mortgage, while Alexander made a personal gain of £3.1 million.

H2O's business model was to use the sewer network to install fibre optic cables and the company had offered services to councils, universities and NHS trusts, the court heard.

Two cities, Bournemouth and Dundee had even reached agreements with H2O to become so-called "fibrecities", connecting every building to its sewer network.

The fraud was eventually exposed when staff at Tendring District Council and Barclays questioned an inflated figure on a contract.

"Principal offender" Dartnell, of King's Lynn, in Norfolk, shrugged at his family in the public gallery as he was sent down for 15 years after being convicted of two counts of fraud by false representation and one charge of giving corrupt payments.

Dartnell's "right-hand man" Alexander and H2O finance director Cumiskey, who were both convicted of two counts of fraud, were jailed for 12 years and 10 years respectively.

And Mundy was handed a seven-year jail term after being convicted of one count of fraud and one of corrupt payments.

H2O's founder, Elfed Wynn Thomas, of Conwy, North Wales, was acquitted of one count of fraud and exonerated by the judge as having been unaware of the Ponzi-style scheme funding his business.

In sentencing the four men at the same court, Judge Michael Gledhill QC said: "The evidence against you is compelling.

"Not one of you has accepted dishonest involvement in these offences. Of course, you have each accepted that with hindsight that fraud was committed, but have sought to exonerate yourselves.

"One of the least attractive aspects of the case has been the attempts of each of you to blame others, including each other, for what happened."