Hundreds of road hauliers are expected to stage a protest in London against the rocketing prices as the strike by oil refinery workers at Grangemouth in Scotland was blamed for contributing to landmark oil prices.

Shadow Chancellor George Osborne also challenged workers' willingness to walk out "at the drop of a hat".

In a further sign of economic gloom, Britain's biggest lender, HBOS, is expected to ask shareholders for up to £4bn this morning as it struggles to cope with the global credit crisis and falling house prices.

The owner of the Halifax and Bank of Scotland would be the second major UK bank to run cap in hand to its shareholders following the Royal Bank of Scotland's decision last week to launch a £12bn rights issue.

Up to 7,000 jobs at the Royal Bank of Scotland are under threat as the company moves to cut costs and shore up its finances.

Lenders are also continuing to tighten their lending criteria, with Nationwide Building Society now capping money for mortgages at £500,000.

Businesses said there was no choice but to pass on rising fuel costs to customers, leaving the prospect of further rises in the price of food and other goods adding further pressure to already stretched family budgets. "It's having a big impact which comes at a very bad time given all the other uncertainties we have at the moment," said Nick Pontone, director of policy for Yorkshire and Humber Chambers of Commerce, who called for the autumn 2p rise in fuel duty to be scrapped.

"One of the things that's happening is companies are starting – after a long period of time where they held prices down – to pass costs on. One of those cost pressures is fuel. The worrying thing is I suspect it's no longer something we could say is a short-term spike."

The average price of a gallon of unleaded petrol has already broken the £5 mark – 109.9p a litre –

Hauliers warn of bankruptcy as petrol hits £5 in Scotland and is expected to reach the landmark across the UK today, according to the petrolprices.com website which monitors prices at more than 9,000 pumps.

It will mean a 10 per cent increase in unleaded prices since the start of the year and comes amid economic uncertainty, rising food and energy prices and concern over falling house prices.

Scottish prices for unleaded petrol rose by nearly 2p a litre during the two-day strike over pensions at Scotland's biggest supplier, Grangemouth, which was due to end at 6am today.

Petrolprices.com founder Brendan McLoughlin warned against panic buying but said: "The strike at Grangemouth has had a huge impact on petrol prices, not just in Scotland."

Referring to rising prices, he said: "Both oil companies and the Government are doing very nicely out of this while the rest of the country is left out of pocket and, in some cases, out of fuel."

Today hundreds of road haulage companies will protest in London against the "rocketing price of diesel".

Mike Presneill, one of the protest organisers, said: "Our industry is the lifeblood of the UK economy.

"Fuel is rising on a daily basis. It is now at levels that are bankrupting hundreds of small and medium-sized haulage companies."

The Road Hauliers' Association said: "More and more hauliers are going out of business. If the 2p increase in fuel duty goes ahead in the autumn then even more will go out of business until, it seems, there are no trucks left on the road."

Shadow Chancellor Mr Osborne said there was a need to confront workers' willingness to go on strike "at the drop of a hat" after speaking at the British Chambers of Commerce national conference, prompting claims of "union bashing" although Conservative sources played down fears of restrictions on the right to strike as Tories review industrial relations laws.

"We are discussing what these changes need to be," said Mr Osborne.

"The series of recent strikes has increased the urgency of what we should do."

He described the teachers' strike as "totally unnecessary" and blamed Prime Minister Gordon Brown for the row at Grangemouth.

Election campaigning in the North West of England yesterday, Mr Brown said: "I'm determined that as a first priority we do everything in our power to help people with the bills, to help people out of this difficult economic situation."