FTSE slides as demand worries knock commodities

* FTSE 100 down 1.8 percent

* Energy, miners hit hard by falling commodity prices

* Financials pressured as crisis continues to weigh

* Retailers gain ahead of sales data

(For more on the financial crisis, click on [nCRISIS])

By Simon Falush

LONDON, Nov 20 (Reuters) - Britain's top share index fell 1.8 percent early on Thursday as a raft of weak data led to a rout in Asian and U.S. stocks, undermining already shaky confidence, with commodity stocks hit by a slide in raw material prices.

By 0900 GMT the FTSE 100 .FTSE had fallen 68.94 points to 3,938.17, after falling 4.8 percent on Wednesday.  Continued...