Drivers are suffering from “unfairly high margins” on fuel sales, a Cabinet minister has been warned.

The Competition and Markets Authority (CMA) must be given the power to take “meaningful action” against companies charging too much for petrol and diesel, according to a letter from the RAC to Energy Secretary Claire Coutinho.

The average retailer margin – the difference between the amount they pay for fuel and the pump price – has been above 18p per litre for diesel since May 7 and is nearly 12p per litre for petrol, RAC head of policy Simon Williams wrote.

The long-term average for both fuels is 8p.

Margins have risen in recent days on the back of wholesale costs reducing due to a drop in oil prices.

The RAC believes if retailers charged “fairer” margins, the average price of a litre of petrol and diesel would be around 145p, down from the current prices of 150p per litre for petrol and 157p per litre for diesel.

To help drivers suffering from these "unfair" margins, here are the cheapest petrol stations for motorists to fill up in and around Southend this weekend, according to *:

Cheapest unleaded prices:

1. Jet Rochford (Starthill service station) - 144.7p

2. Tesco Southend Extra - 145.9p

3. Esso Rayleigh Road (Eastwood Express) - 146.9p

4. Esso High Street (Canvey service station) - 146.9p

5. BP Rochford Business Park - 147.9p

Cheapest diesel prices:

1. Jet Rochford (Starthill service station) - 152.7p

2. Texaco Southend (Park standard filling station) - 153.9p

3. Tesco Southend Extra - 153.9p

4. Esso High Street (Canvey service station) - 153.9p

5. Asda Shoebury Automat - 154.7p

*Prices are correct as of Friday, May 17