By Sarah Turner

British shares surged Thursday, with the FTSE 100 index moving back over the 4,000 mark for the first time since February amid hope that the economic backdrop may be improving.

London's widely followed benchmark climbed 4.3%, rising 169 points to 4,124.97 in the first time the index has traded over 4,000 since Feb. 19 and giving the index its third straight session of gains.

"The FTSE 100 is back through the psychologically important 4,000 level, driven by some strong U.K. and U.S. numbers over the past few days," noted Mark Foulds at ETX Capital.

"The start of the G20, and the likelihood that we will get a global agreement on tackling the financial crisis, is also giving the market a boost," he added.

Stocks in the U.S. and Europe also rallied.

Beaten-down banks were one of the key drivers behind London's advance, with shares of Standard Chartered rallying 15.9%, HSBC Holdings (HBC) gaining 11.8% and Barclays (BCS) adding 7.3%.

In addition to indications of an improving economy, bank shares were lifted globally on a relaxation of accounting rules.

A rally for oil and metals futures lifted a host of commodity producers.

Copper extractor Kazakhmys leaped 17.4% and diversified miner Anglo American tacked on 12.1%.

One of the few fallers was Randgold Resources (GOLD), shedding 4.5% as gold futures tumbled more than $25 an ounce.

Housing data

There were more positive economic data out in the U.K. on Thursday: Nationwide Building Society said U.K. house prices unexpectedly rose 0.9% during March, the first such increase since October 2007.

Among shares of home builders, Barratt Developments soared 20.2% and Persimmon moved 11.6% higher.

Shares of Taylor Wimpey also shot up, adding 23.4%. The Financial Times newspaper reported that the company has reached a reached a deal with lenders on restructuring its debt.

Also outside the top index, shares of sugar producer Tate & Lyle climbed 6.7%.

The company said pretax profit for the year ended March 31 will be "marginally below" what it had previously forecast. Previously, management had projected that Tate & Lyle would generate pretax profit roughly in line with the prior year.

Still, profit mix has reduced the company's tax rate, so earnings per share are expected to be broadly in line with market expectations.

Tate & Lyle also said that the U.K. sugar market remains extremely competitive and that profit performance at the division will be modest until the next institutional price change in October.