Prime Minister David Cameron's approval rating hit its lowest level since he took office, a poll showed, after his Conservative party came under fire for an unpopular budget, cosy ties to rich donors and a botched handling of a looming fuel strike.

In the worst public relations week for the Conservative-Liberal Democrat coalition government since it took power in 2010, Labour surged ahead in the YouGov/Sunday Times poll to 42 points, a nine-point lead over the Conservatives.

The shift comes as newspapers traditionally supportive of the government are accusing ministers of being out of touch with ordinary peoples' lives in a time of economic stagnation.

The March 21 budget, which cemented the government's seven-year austerity plan, cut income taxes for the biggest earners but raided tax reliefs for the elderly, compounding the Conservatives' image as a party favouring the wealthy.

The budget also contained a tax hike for hot foods such as meat pasties, a popular pastry snack, giving Labour fuel to accuse ministers of not understanding the lives of most voters.

In an embarrassing admission, Finance Minister George Osborne said he could not remember the last time he ate a pasty from Greggs, a cheap bakery chain favoured by working people.

Cameron, whose popularity rating dropped 15 points to -26, failed to convince when he said he was a fan of the snack and had last bought one at an outlet inside the train station in the northern city of Leeds. That outlet had closed in 2007.

The party was hit by another scandal this week following an investigation by newspaper reporters who uncovered that a Conservative treasurer offered access to the prime minister in return for a hefty donation to the party.

Ministers were also fiercely criticised for triggering panic buying of fuel after they reacted to a potential strike by petrol tanker drivers by urging motorists to keep their cars topped up and hoard petrol in cans at home.