Economic recovery hopes were reignited as the FTSE 100 Index returned to growth after a six-day winning streak ended on Monday.
Commodity-based stocks dominated the risers board after the Asian Development Bank upgraded its growth forecasts for major economies like China and India and said the region looked set to lead a global recovery.
With the price of oil overcoming a recent slump to climb back above 70 US dollars a barrel, the Footsie reversed all of the losses seen in trading to climb 1% or 46.5 points to 5180.8 by mid-morning.
The mood in the mining sector was given a further boost by news from Rio Tinto that it is selling more Alcan assets.
Rio shares lifted 4% or 93.5p to 2737.5p, while Kazakhmys added 28p to 1115p and Lonmin cheered 70p to 1769p.
Elsewhere, drug firm Shire was 25p higher at 1094p after broker Jefferies raised its rating amid hopes of earnings growth next year.
And a recent broker upgrade from Societe Generale gave a further lift to Marks & Spencer shares ahead of a trading update from the retailer next week. The stock was up 10.4p at 384.8p, a gain of almost 3%.
The latest surge in market confidence prompted investors to switch out of traditionally defensive stocks, causing United Utilities to fall 11.3p to 454.2p and Severn Trent to drop 23p at 975p.
In stock market news, building firms were the centre of attention after the UK's competition watchdog fined 103 construction companies a total of £129.5 million for bid-rigging.
They included Carillion, which fell 5.7p to 282.4p after being hit with a £5.4 million fine.
