* FTSE 100 up 0.3 percent, seen challenging 6,820 level
* Burberry rises after reporting higher Christmas sales
* GlaxoSmithKline buoyed as SG adds to "premium list"
LONDON, Jan 15 (Reuters) - Britain's top equity index rose to its highest level in two-and-a-half months on Wednesday, helped by the World Bank's upward revision of global growth forecasts and gains at luxury group Burberry.
The blue-chip FTSE 100 index rose by 0.3 percent, or 21.15 points, to 6,788.01 points in mid-session trading.
Luxury goods group Burberry topped the FTSE 100's leaderboard with a 4.8 percent rise after reporting higher revenues over the Christmas period.
Healthcare group GlaxoSmithKline also rose 1.1 percent to add the most points to the FTSE, which traders attributed to SocGen's decision to add it to its "premium list" of favoured stocks.
The FTSE 100 rose 14.4 percent in 2013 to post its best annual gain since 2009.
The UK stock market has been buoyed by a gradual recovery in the British economy, and further signs that global trade is picking up after the 2008 financial crisis came after the World Bank raised its forecast for global growth for the first time in three years.
"The general outlook today has been fairly positive, helped by the World Bank upgrade," said Hantec Markets analyst Richard Perry.
Perry saw the FTSE challenging highs of around 6,820 points reached in October, and said investors should use any pullback to buy up equities for relatively cheap prices.
Charles Stanley analyst Bill McNamara also saw the FTSE reaching the 6,820 point level in the near-term and added the UK market was slowly building up a position to move higher.
"The impression is that the UK index is starting to find its feet."