Hospital bosses were forced to pay out more than £8m to a Russian gas firm after bills stacked up.
Bills of £5.4m and £2.6m were paid to Moscow based gas giant Gazprom in February and March respectively by Calderdale and Huddersfield NHS Foundation Trust.
The normal gas bills are between £150,000 and £250,000 per month.
The hospital trust has said the huge sums were payments dating back four years.
But the trust’s publications that detail all spending over £25,000 show five and six figure outgoings to Gazprom almost every previous month in the past two years.
Associate Director of Estates and Facilities, Dave McGarrigan, said: "The February invoice is an amended account for the supply of gas for Huddersfield Royal Infirmary, Calderdale Royal Hospital and 15 community sites.
“In September 2014, the Trust undertook a review of utility invoices across all our premises and discrepancies were identified with VAT at the two hospital sites.
“The supplier adjusted future rates, and as a statute requirement, looked back over the four previous years. Further discrepancies were highlighted, and the Trust received a credit of £75,000.
“The Trust is committed to reviewing its utility consumption and ensuring that the correct rates are applied.”
Financial records show further large bills have been incurred over the past six months including, £2.6m in rates to Kirklees Council, £2.8m rates to Calderdale Council, more than £2m to electricity supplier Npower and £180,000 to Yorkshire Water.
The total utility bill for period December 2014 to May this year comes in at a cool £16m.
Other significant bills include over £567,000 on laundry costs, following the closure of the in-house laundry department last year.
