Three men jailed for 13 years for their part in a multi-million pound fuel and VAT fraud have been ordered to pay back almost £6.9m or face more time behind bars.

Michael Wilmot, 73, led the Lincolnshire gang that was jailed in July 2014 after an investigation by HM Revenue and Customs (HMRC) found they had evaded millions in duty and tax through a sophisticated fraud.

Wilmot used connections to a farmers’ buying consortium in Louth to order large quantities of rebated fuel, commonly known as red diesel. Unknown to the consortium, the fuel was sold on and used illegally in heavy goods vehicles (HGV) belonging to 35 different companies, all with connections to Wilmot.

In an extension of the fraud, Wilmot played his part in issuing invoices for the haulage work carried out by the companies, charging customers VAT on their services. But instead of paying the VAT to HMRC, he pocketed the cash. In addition, none of the companies involved paid Corporation Tax or PAYE and National Insurance for their drivers and employees.

Wilmot, and transport manager Michael Taylor, were jailed for seven years and four years respectively. In February this year HGV driver Derek Blackburn was sentenced to 16 months in jail for his part in the fraud, plus seven months on an unconnected charge of perverting the course of justice.

This week at Hull Crown Court Wilmot and Taylor were ordered to pay back £6,884.366.97 within three months. If not, Wilmot will receive a default prison sentence of three years and Taylor, a default prison sentence of 18 months. Blackburn was ordered to pay £12,500 within three months or a default prison sentence of eight months.

There is no appeal against default jail sentences issued in confiscation orders and the order for repayment remains in place after the default sentence is served by the fraudster.

David Cowie, assistant director, Fraud Investigation Service, HMRC, said: “Our investigations do not stop at sentencing. It is crucial we look to stop criminals profiting from their crimes and reclaim as much as possible to put it back where it belongs – funding vital public services across the UK.

“This criminal gang were put behind bars for stealing millions of pounds. Now they must pay back what they owe otherwise they will be spending more years in prison.”