The RAC predicted that petrol and diesel pump prices will go up by around 3p per litre in the next fortnight after the "flash crash".
The breakdown rescue firm's fuel spokesman, Simon Williams, said: "The unexpectedly sharp fall in the value of the pound will make the wholesale price of fuel go up.
"Sadly, it's also happened at a time when the oil price appears to be rising again so the combined effect will be bad news for motorists."
After oil producing group Opec reached a deal last week to stabilise the market by slashing output, the cost of a barrel has gone up by six US dollars.
These factors have seen pump prices increase from lows of 97p a litre in January to well over £1.10p a litre now.
The current average price of diesel is at its highest since August 2015.