Savers in banks and building societies will have the first £35,000 of their deposits 100 per cent guaranteed from today under reforms to prevent a repeat of the Northern Rock affair.

Alistair Darling, the Chancellor, will announce that the change, which comes into effect immediately, is a prelude to a complete overhaul of the compensation system to be included in legislation in the next session of Parliament.

Mr Darling said last week that he was looking at giving Britain a US-style system of savings protection, under which deposits held in a collapsed bank would be moved into a special vehicle and paid back to savers within days.

The scheme would be one of several measures to return confidence to the system and allow the Bank of England to carry out its role as a lender of last resort.

Mr Darling indicated that deposits of up to £100,000 might be protected, although the final figure has yet to be fixed.

Under the current rules, depositors get 100 per cent of the first £2,000 but only 90 per cent of the next £33,000.

Today’s change by the Financial Services Authority to the compensation scheme will make the figure £35,000 with a 100 per cent guarantee.

Mr Darling, speaking alongside Alan Greenspan, former Chairman of the US Federal Reserve, will make it clear that this move is just the first step in improving the financial services compensation system.

Mr Darling will say that in a global financial market no country or company can insulate itself entirely from international risk. “If a problem does happen, we need to be able to deal with it quickly to maintain stability and confidence.

Savers need to be sure that they can get their money out if they need to.

“That is why in the current market circumstances we are providing a guarantee for Northern Rock’s depositors. But for the future, we now need to put in place a better regime.”

Yesterday Conservatives accused the Government of inconsistency because its treatment of Northern Rock was exceptional.

To stop the run on the bank, the Government guaranteed the full deposits of investors as opposed to the limited sum of £35,000 which is being proposed today.

George Osborne, the Shadow Chancellor, said: “Alistair Darling has piled confusion upon confusion. Why did he tell one newspaper that savings would be guaranteed up to £100,000, only to change his mind ten days later and offer protection at a much lower level? What people want in a period of financial instability is certainty, not fiddling.”

Michael Fallon, a senior Tory on the Treasury Committee, added: “Northern Rock has been given preferential treatment throughout. The compensation scheme is chaotic.

"They are making it up on the hoof. The amount keeps changing. Is it going to go down to £10,000 in a week. I thought it was going to be £100,000 a week ago.”

But an aide to Alistair Darling dismissed the criticism, saying that today’s move was just the first step in a wider move. Subsequent changes to the compensation system will now be the subject of consultation.

The aide said: “Today’s announcement is just a first step. It is irresponsible to suggest that we would implement a full scheme without consultation. We want to establish a system that works.”

The scheme was set up in 1997, bringing together the existing compensation schemes from the different financial sectors into a single scheme. It raises money from the industry to pay out on claims.

In the interview with The Times Mr Darling suggested that eventually setting a figure of about £100,000 for guaranteeing deposits would encourage big savers to spread their money around.

He promised changes to regulation to bring in far greater transparency and prevent big investments being hidden off the balance sheet, and to enable people to know the risks to which they were exposed.

He wants greater focus on banks’ liquidity as well as their solvency – Northern Rock had been considered solvent but it had liquidity problems.

And regulators will have to focus on banks that seem to be doing well as well as those doing badly.

Mr Darling also wants changes to the Bank of England’s lender-of-last-resort system so that an institution would not be dissuaded from applying for help.

The run on Northern Rock began when its request for help from the Bank of England was made public.