The FTSE top shares pushed higher in early trade on Tuesday, led by strength in commodity stocks after U.S. aluminium firm Alcoa posted forecast-busting Q4 results, and with copper prices firmer on upbeat data from top metals consumer China.

Miners <.FTNMX1770> advanced after Alcoa, the largest U.S. aluminium producer, kicked off the U.S. earnings season with fourth-quarter revenue that beat expectations, though a plunge in aluminium prices helped push the firm into a loss.

Strength in copper prices also supported the miners after data that showed a rise in imports of the metal by China, which accounts for 40 percent of the refined metal's global consumption.

Concern that China's economy might slow more than forecast had .. (been) subduing buyers of metals and basic material stocks in recent weeks, increasing volatility and soaking up liquidity to markets braced for significant stress should sellers' fears be realised, said David White, trader at Spreadex Ltd.

At 09:02 a.m. BT, the FTSE 100 <.FTSE> index was up 46.63 points, or 0.8 percent at 5,658.89, having closed down 0.7 on Monday.

Integrated oils <.FTNMX0530> also supported the FTSE 100 index as crude prices jumped 1.2 percent, with Royal Dutch Shell up 0.8 percent.

Oil explorer Cairn Energy was also among the top blue chip gainers, up 3.0 percent, after the company said it would return $3.5 billion (2.2 billion pounds) of cash to shareholders following completion of the deal to sell a majority stake in its Indian business to Vedanta Resources .

In reaction Oriel Securities upgraded its rating for Cairn Energy to add from hold.

Banks <.FTNMX8350> also rallied after falls in the previous session, with part-state-owned Lloyds Banking Group gaining 2.3 percent.

RBS added 1.7 percent. Also part-state-owned, RBS is likely to cut between 3,000 and 4,000 investment banking jobs as part of an overhaul of the business to be unveiled this week, a person familiar with the matter said.

RETAIL RELIEF

Retail investors found relief in Christmas trading updates from both blue chip Marks & Spencer and mid cap <.FTMC> Debenhams which shone light on the high street gloom.

M&S, Britain's biggest clothing retailer, gained 2.4 percent after it said sales at British stores open over a year rose 0.5 percent excluding VAT sales tax in the 13 weeks to December 31. That compared to a 0.7 percent fall in the second quarter.

The shares have had something of a hangover since the last trading update in November, but this marginal increase in fortunes should restore some confidence, said Richard Hunter, head of equities at Hargreaves Lansdown Stockbrokers,

Meanwhile, Debenhams, Britain's No.2 department store group, topped the FTSE 250 <.FTMC> leader board, up 9.5 percent, after it posted a slightly better than expected performance in underlying sales in the last 18 weeks as deep discounts lured customers in the run up to Christmas.

A survey from the British Retail Consortium, released on Tuesday, showed British retailers finished 2011 with the best sales growth in months as hefty discounting lured in shoppers, although weak business a year earlier flattered the figures.

In other cautiously upbeat domestic data, a survey by the Royal Institution of Chartered Surveyors said British house prices fell at a marginally slower pace in the three months to December.

Tempering the optimism, BofA Merrill Lynch downgraded its rating for the world's No. 3 retailer Tesco , which will issue a trading update on Thursday, to neutral from buy.

We think Tesco will struggle to revitalise sales ahead of results in April where management likely will lay out a strategy for capital-efficient growth, Merrill said in a note also cutting its estimates for Tesco by 1-2.5 percent and reducing its target price to 420 pence from 440 pence.

There were only a handful of other blue chip falls, with drugmakers the worst performers led by GlaxoSmithKline down 0.4 percent, extending Monday's falls which followed slightly downbeat drug filing news.

(Editing by Sophie Walker)