FTSE slides 1.6 pct as U.S. outlook darkens

* FTSE 100 down 1.6 percent

* Energy, mining stocks fall with oil, metals prices

* Retailers gain after sales data beats expectations

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

By Nick Vinocur

LONDON, Nov 20 (Reuters) - Britain's top share index was down 1.6 percent by midday on Thursday, as dire forecasts for the U.S. economy led to sharp falls in commodity prices, denting energy and mining companies.

By 1158 GMT the FTSE 100 .FTSE had fallen 62.41 points to 3,943.03, after falling 4.8 percent on Wednesday.

In the U.S., the Federal Reserve slashed its economic growth forecasts and consumer prices fell at a record pace last month, while Japan's October exports fell at their fastest pace in seven years.

The news heightened fears that demand for energy and commodities would slump, sending crude CLc1 down for a fifth consecutive session to below $53, as weaker metal prices put more pressure on miners.  Continued...