So says the RAC Foundation following the publication of its report on the changing face of oil and fuel production.

The research, undertaken by Deloitte, highlights that in 2001 the UK's high oil production meant the country could export 40% of it. This compares to a decade later, where 32% had to be imported.

The UK’s ageing oil refineries are also struggling to meet the demand for diesel caused by the growing number of diesel cars on the road. While the UK is a net exporter of petrol, it is a net importer of diesel, having to bring in as much as an estimated two weeks' worth of annual usage.

Currently the UK’s biggest sources of imported diesel are other European countries – predominantly the Netherlands, Sweden, Russia and Belgium – and the US.

Professor Stephen Glaister, director of the RAC Foundation, said: ‘The recent debates on security of supply have centred on our gas and food needs, but our inability to meet our oil and roadfuel requirements is a potential time bomb. We are becoming more dependent on international markets and foreign suppliers to keep the nation moving.

‘Not only are our North Sea oil reserves being depleted, our ageing refineries are not configured to produce the quantity of diesel we use. Retro-fitting these plants would cost many hundreds of millions of pounds; money the industry is unwilling to spend. As the closure of the Coryton refinery in Essex demonstrates, the big players are seriously considering selling up or closing down.

‘As the global economies recover we will be competing with emerging nations like India and China for scarce resources. Even if we can secure the fuel we need from abroad, unforeseen events – war, politics, weather – all threaten the stability of the supply chain and will have an impact on price.

‘Diesels now account for half of all new car sales and just about 100% of lorries run on diesel. The consequences of a major disruption to supply will be enormous.’