Petrol prices continued to climb yesterday as experts predicted they will hit £6 a gallon by September.

The average price of unleaded has crashed through the £5 (110.2p a litre) mark- meaning a £61 bill to fill the typical tank.

But by the end of summer drivers could be paying £6.81 a gallon (£1.50 a litre). It would raise the average cost of filling a tank by 37% to £84.

The £1.50-a-litre prediction was made by price comparison experts at uSwitch. com.

Its consumer policy director Ann Robinson said: "The outlook is bleak.

Petrol prices are predicted to increase a further 37%.

"Drivers who are reliant on their cars for business or live in remote areas will be hardest hit." Brendan McLoughlin, of comparison site PetrolPrices. com, said: "It's up to the Government to put pressure on OPEC to increase production so that prices fall.

Motorists have even been asked to boycott petrol from Esso and BP.

Campaigners say the two giant suppliers would then be hit and forced to act to reduce prices.

Once petrol hits £1.50 a litre the average annual motoring fuel bill will be £2,637.

The past weeks have seen a series of record oil prices with crude oil nearing

120 a barrel on Monday.

A Daily Star investigation yesterday found the dearest unleaded in the UK at 132.9p, diesel at 135.9p and LPG at 59.9p.

The cheapest unleaded we found was 105.9p, diesel at 114.9p, and LPG at 48.9p.

Meanwhile, it also emerged yesterday that parking wardens or speed cameras trap one in three drivers every year.

The total rises to more than four in 10 when the number of motorists caught by the police is included.

David Ruffley , Tory police spokesman, said: "The numbers of drivers being nicked by cameras has risen by a colossal 615% in 10 years, from 323,200 in 1997 to 1,986,200 in 2006.

"This is another staggering statistic that tells us a lot about the surveillance society."