Britain's top shares rose on Wednesday, boosted by banking stocks and miners as a reassuring start to the US earnings season boosted investors' appetite for riskier assets.

The FTSE 100 was up 24.33 points, or 0.4 percent, at 6,077.96 by 11:07 SA time, resuming a rally that took it to its highest closing level since early February 2011 on Friday, having slipped on Monday and Tuesday of this week.

Miners gained as investors welcomed news that Alcoa, the largest aluminium producer in the United States, posted in-line fourth-quarter earnings after the Wall Street close on Tuesday and offered a positive outlook for 2013. But it kept a cautious tone as worries linger over a looming US budget confrontation.

“The comments from Alcoa... put people more into a risk-on perspective. But if you wanted to buy (the market) on the Alcoa results it's probably tempting fate somewhat because it's (just) one set of results,” Andy Ash, head of sales at Monument Securities, said.

“I think a lot of what we are seeing is new year flows, so retail (investors) putting money into equity funds ...- and you don't want to fight against that. But that tends to run out in the third week of January which coincides with (when the reporting season gets under way in earnest).”

Banks led blue chips higher, with Lloyds Banking Group the best performer, up 3.3 percent as traders cited the impact of a UBS upgrade to “buy” from “neutral” with an increased target price of 60 pence.

“Lloyds' investment strategy is simplest of the UK domestic banks. The story is defined with the group focused on execution,” UBS said in a note.

“We think Lloyds will deliver rising margins, falling costs and falling provisions, which will provide a very strong upswing to profitability and EPS momentum over the next few years.”

J Sainsbury suffered early falls, off 2.5 percent and relinquishing the previous session's advance as it issued a trading update which prompted Seymour Pierce to cut its rating on the stock to “reduce”.

Britain's No. 3 supermarket met forecasts for underlying sales in the Christmas quarter, though growth did slow from its first half in a highly competitive festive market.

“We suspect Sainsbury will struggle to outperform in 2013 as Tesco continues its fight back and there is some margin vulnerability as momentum slows,” Seymour Pierce said in a note.

Many of Britain's grocers are finding the going tough as consumers fret over job security and a squeeze on real incomes, and with the retail market showing minimal growth, store groups are battling to take market share off each other.

For a graphic showing UK retailers' share price performances click on:

Tesco, which reports on Thursday, shed 0.8 percent. - Reuters