Speaking to Fleet World, Mr Kendrick commented: 'I expect that if employees provide employees with a fuel card for their business mileage only that they need to be carefully monitoring their claims to ensure business mileage only is being reimbursed. It is often the case that those employees who have arrangements of this nature will only be reporting a small amount of private mileage.'

His comments come following major rises in the price of fuel due to global oil prices and the recent VAT and fuel duty hikes. The average UK price for petrol on 1 February was 128.65p per litre, while diesel was 133.38p.

Earlier this week mileage audit specialist TMC warned fleets to be on the lookout for exaggerated fuel claims, saying that on average in the private sector there is a 25% drop in mileage expense costs after they are properly audited, meaning that up to a quarter of fuel claims by UK employees may be fraudulent. This amounts to an estimated annual fraud cost of up to £1.6 billion for fuel claims alone.

However, fleets could face more than just increased fuel bills by allowing drivers to claim for private mileage.

Mr Kendrick said: 'It is not uncommon for HMRC to look carefully at this and there have been cases where the level of private mileage does not equate to the commuting mileage undertaken by employees. I suspect that with the increase in cost of fuel we will see a lot of attention in this area from HMRC.'