THE Government has refused to disclose to the Office for Budget Responsibility if it made any financial promises to Japanese carmaker Nissan, documents released today have shown.

The OBR's economic outlook report, released alongside the Autumn Statement, reveals that the fiscal watchdog "asked specifically whether any contingent liabilities had been created in respect of assurances provided to Nissan and the Treasury declined to say".

Last month, Nissan said it was extending production of two new vehicles in Sunderland amid rising speculation that it could ditch the UK following the country's decision to quit the European Union.

The move secured 7,000 jobs in the Brexit-backing city, but prompted a volley of questions over whether a so-called "sweetheart deal" between the carmaker and the Government had been struck.

In compiling its forecasts, the OBR also asked the Treasury which department's accounts the Government expects any liabilities to be reported.

However, the OBR said: "Unfortunately, the Treasury declined to address the substance of our question, telling us instead that 'There is a standard process for departments to report to Parliament as and when they incur contingent liabilities. Any commitments incurring costs will be managed within existing overall DEL totals.'"

Ministers have strongly denied suggestions they offered the firm a sweetheart deal but have refused to publish a letter of reassurance sent to Nissan boss Carlos Ghosn.

The Government has insisted that there are no liabilities relating to its assurances "as it currently stands", but refused to be drawn on whether this will change once Britain leaves the European Union.